A female northern black widow (Latrodectus variolus). Photo by Jim Jasinski, Ohio State University Extension, Bugwood.org.
I take issue with the title’s phrasing, but, in a way, it’s true—the northern black widow (Latrodectus variolus) could be considered an “infrequent inhabitant” of southern and central Maine. And, unlike our hundreds of other spider species, it’s highly venomous.
That hasn’t stopped me from assuring Mainers who call me about spiders that unless they’ve been traveling or opened some strange packages, they don’t have to worry about species of medical concern.
Yes, L. variolus has been reported here, and given its distribution in nearby states and provinces, it could be indigenous. But folks have been saying this for decades. While each warmer winter probably brings L. variolus closer to establishing a firm population here (modeling even predicts it), there’s little evidence that it already has. We still don’t have the collected specimens or scientific studies to suggest a continuous presence. Individual L. variolus spiders show up occasionally—that’s it. Other highly venomous spiders, like the southern black widow, western black widow, and the brown recluse, appear too. The difference is that these spiders are almost certainly one-offs transported here by human activity. With L. variolus, it’s less clear.
But if you want to go looking for trouble…
The northern black widow has a line of red markings down the top of its abdomen along with the broken hourglass marking on the underside. Photo by Sam Droege.
Adult female L. variolus are easy to recognize at around one-half inch long with a glossy black, bulbous abdomen and conspicuous red markings. The pattern on the northern black widow’s underside usually appears as two separate triangles rather than a complete hourglass. In addition, L. variolus typically bears a line of red spots down the back of the abdomenand may have pale, yellowish stripes when young.
Male black widows are much smaller and lack the mature female’s enlarged, rounded abdomen. Their tiny fangs can’t puncture human skin well enough to deliver venom. Males have yellowish/whitish bands and halos around their red spots. Young juveniles are brownish or tan with white or yellowish markings similar to males.
Don’t get wrapped up
A black widow with her egg sac. Widow spiders weave tangled, disorganized webs. Photo by Josh Shoemaker, Bugwood.org.
Black widows belong to the cobweb weaver spider family (Theridiidae). They construct tangled, ugly webs of thick silk, often in cavities like rodent burrows or bait stations, hollow stumps, crevices in rock walls and wood piles, baskets, boxes, and—very unfortunately—shoes and outhouse holes. Mature females stick close to their webs. If you think black widows are around, don’t stick a body part in a dark nook without inspecting it first.
Male northern black widows don’t live as long as females—especially if they can’t escape their lady’s web. Photo by Jana Miller.
The life of the widow
Black widows get their name from the female’s habit of devouring her mate, but many spider species eat slow or clumsy males. That’s the risk the little guys run when they stride into the territory of a larger predator and start annoying her. If the male can’t escape after accomplishing his mission, at least his corpse will nourish his progeny.
We don’t know very much about L. variolus and its life cycle. If the species is like its southern relative, females could produce several egg sacs per season, each giving rise to a couple hundred spiderlings. Once they leave the sac, the bitsy brood deploy silk strands into the wind to carry them to new homes. It takes a few months and several molts for them to reach maturity. Female black widows can live up to a year and a half. Males don’t live as long.
Our bark is worse than their bite
Spiders don’t want to bite us. Most will try to run for their lives when we lumber too close, including L. variolus. Bites usually occur because we inadvertently squish the spider against our skin.
Not only are black widows rather skittish, but their deadly reputation is also exaggerated. Few fatalities have resulted from their bites—the last one reported in the United States occurred in 1983. Those most at risk of death or long-term complications include young children, the elderly, and individuals with heart conditions.
Still, bites are serious. Anyone bitten by a black widow should call poison control and seek medical attention right away. The bite site rarely hurts or swells much, but the black widow’s neurotoxic venom acts throughout the body. It can cause excruciating pain (especially in the abdomen), nausea, tremors, high blood pressure, rapid heart rate, difficulty breathing, and other unpleasant symptoms.
For the record, all spiders are venomous. Even the adorable ones. But only a few can deliver highly toxic venom in dangerous doses. Photo by Joseph Berger, Bugwood.org.
Avoid Shelob’s lair
Although the odds of encountering L. variolus in Maine are exceedingly low, we can do a few things to reduce the number of spiders in our homes and avoid spider bites in general. Cluttered, undisturbed areas provide excellent habitat for many species. So, sweeping, dusting, and tidying up can convince spiders to leave. Closing any gaps and cracks around doors and windows will help keep them out in the first place. Wear gloves when working outside around woodpiles, rock walls, and other debris to prevent bites. Check boots, shoes, and gloves stored in basements, attics, garages, and sheds before putting them on. And if you’re upta camp, check the hole in the outhouse before sitting down!
RESOURCES
Barry, D., and G. Fish. 2010. Structural and General Pest Management – Maine Pesticide Applicator Training Manual: Category 7A. University of Maine Cooperative Extension.
Jennings, D.T., and C.P. Donahue. 2020. A Checklist of Maine Spiders (Arachnida: Araneae). Forest Health and Monitoring Maine Forest Service Technical Report No. 47. Maine Department of Agriculture, Conservation and Forestry.
Wang, Y., N. Casajus, C. Buddle, D. Berteaux, and M. Larrivée. 2018. Predicting the distribution of poorly-documented species, northern black widow (Latrodectus variolus) and black purse-web spider (Sphodros niger), using museum specimens and citizen science data. PLoS One. 13: e0201094. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0201094
Ah, the mosquito. Who isn’t familiar with it? The buzz in your ear, then the sting as you smack yourself in the side of the head.
And, boy, are they out with a vengeance this year. If you live in the less-paved parts of New England, you’ve probably noticed their higher-than-average abundance. We’ve had one of the rainiest summers on record here in Maine, which means the mosquitoes have found themselves with all the stagnant water they could wish for.
In a typical year, most of these woodland pools would have dried up weeks ago.
I’ve gotten calls for weeks from folks under siege, asking what they can do to manage these marauding monsters, several willing to resort to chemicals for the first time. One client joked about replacing his bug zapper with an electric chair. I can relate. My shadowy, forested lair is a mosquito haven in a dry year. This summer? I’m keeping the dogs on leashes so the conniving culicids can’t fly off with them.
The deadliest animals on earth
Mosquitoes aren’t just an itchy nuisance. They sicken millions annually by vectoring the malaria, dengue, and yellow fever pathogens, among others. The cost is tremendous in some parts of the world, not only in lives and misery but the billions spent to treat those illnesses and manage mosquitoes.
In the U.S., mosquitoes don’t quite hold our health and economy hostage, but they’re still a serious pest and public health threat. Dozens of people die here every year from mosquito-borne diseases, and hundreds more become severely ill.
A dainty demon
The head and mouthparts of a mosquito that I “accidentally” decapitated in self-defense.
Adult mosquitos are slender and long-limbed. Their scaly wings and the syringes on their faces set them apart from other delicate flies. Very different from the adults, the limbless larvae wield brushes, which they use to strain food particles from their aquatic environment. The heads and thoraxes fuse and enlarge when they become pupae, creating odd, comma-shaped critters, while the abdomen remains free to propel them through the water.
Tropical terror
Mosquitoes even plague the Arctic during the short time when they’re active, sometimes descending in horror-movie-esque swarms.
As with many other insects, mosquitoes are most abundant in the tropics, both in the number of species and individuals. Mosquitoes fly whenever the temperature reaches 50 ℉ and can breed continuously in places where it rarely drops below this temperature, allowing them to run rampant.
That’s not to say temperate regions don’t have plenty. In Maine, we have more than 40 species, and there’s enough flying around that they spill into my home and car every time I open the doors.
The only places mosquitoes don’t terrorize mammals and birds are the Antarctic and, for reasons that scientists have yet to elucidate, Iceland.
The productivity of puddles
Mosquitoes’ life cycles and habits vary widely by species, but they have one thing in common—their larvae need standing water. Without water, mosquito eggs won’t hatch. Depending on the species, as little as a bottlecap’s worth will do. While some mosquitoes breed in relatively fresh, clean water, others thrive in polluted, opaque stews, brackish backwaters, or briny salt marshes.
In Maine and other northern regions, transient pools formed by melting snow provide the perfect mosquito habitat for churning out late spring and early summer biters. Other prime larval habitat includes small ponds, ditches, tree holes, culverts, clogged gutters, unchlorinated pools, rain barrels, buckets, pet bowls, tarps, and tires. Mosquitoes love tires. They don’t love flowing water. So keep it moving or dump it out.
Mosquito life cycles
Females deposit their oblong offspring on the water’s surface or in depressions destined to flood. Some eggs can survive for years, waiting to be unleashed after flooding rains. Once the eggs hatch, most larvae hang out upside down just below the water’s surface. There, they can breathe through tubes or holes on their hind ends and feed by straining microorganisms or decaying matter from the water column until disturbed. Then they’ll wiggle, convulsing toward the sediment to escape predators. The larvae molt three times before they pupate. Unlike most insects during this stage, mosquito pupae know how to get around. They thrash their abdomens to propel themselves toward the depths. Adults emerge from pupae at the water’s surface and float on their cast skins while their wings dry. They can live for up to a couple of months in humid conditions. In warm weather, some species complete their life cycles in a week. Where mosquitoes must overwinter, most do it as eggs or adult females, but a few species overwinter as larvae.
Blood and nectar (I think that’s what I’ll call Book 3)
Adult mosquitoes fuel their flights with sugars from nectar and sap. Though delicious, these fluids don’t supply the proteins needed for egg development. That’s why females hunt for a blood meal before laying their eggs. Some feed every few days to nourish each new batch. A mosquito’s preference varies by species. Though many bite birds and a few feed from frogs, most mosquitoes pursue mammals. Some will drink blood from just about whatever has it.
Aedes aegypti, the yellow fever mosquito. This invasive, container-breeding insect is common in the southeastern and midwestern U.S. It can vector several imported diseases. Photo courtesy of USDA-ARS by Stephen Ausmus.
Like any good vampire, the mosquito stalks its prey from the shadows. Plenty bite during the day, but they desiccate quickly out in the open on a hot, sunny day. So, many species concentrate their activity around dusk and dawn. Often some shady vegetation or cloud cover provides all the darkness they need to cause havoc.
Mosquitoes usually hunt within a few miles from home. They make short flights, then rest in protective vegetation, hopscotching their way to blood.
Mosquitoes that create buzz
The purple pitcher plant, Sarracenia purpurea, is the center of W. smithii’s world. Photo courtesy of USFWS by Thomas G. Barnes.
My favorite culicid—the aptly-named pitcher plant mosquito (Wyeomyia smithii)—develops in water collected inside the carnivorous pitcher plant. It even overwinters there, frozen in pitcher-shaped chunks of ice. This species doesn’t require a blood meal, obtaining all the protein it needs as larvae from the remains of the pitcher plant’s prey.
One mosquito species, Uranotaeniasapphirina, sucks the blood of worms and leeches.
The larvae of the cattail mosquito, Coquillettidia perturbans, breathe by poking a tube into the oxygen-rich tissues of cattails and other aquatic plants rather than hanging out at the surface.
Females of the eastern salt marsh mosquito (Ochlerotatus sollicitans) will hunt up to 100 miles from their salty origins for blood.
Instead of filter feeding, the larvae of some Toxorhynchites species prey upon other mosquito larvae.
Purveyors of parasitic protozoa
The ability of some mosquitoes to vector Plasmodium parasites, the cause of malaria, makes them humanity’s worst animal enemy. Females of the genus Anopheles pick up these parasites from infected individuals forever after injecting them into people they bite. The parasites migrate to the liver, then multiply before infiltrating and destroying the host’s red blood cells. They’ve been at it since before humans were humans and spread across the globe with us. Today, malaria’s burden falls on poor, tropical regions where it still kills hundreds of thousands (80% of them young children) each year and sickens millions more. But malaria once plagued most of the world, including much of Europe and the United States, up into Canada. With intense mosquito management, improved living conditions, and medical advancements, this disease was eliminated from most of North America. Still, with malaria so prevalent in some areas and so much international travel, around 1,700 cases come into the U.S. annually. The mosquitoes that vector malaria remain here and sometimes bite infected travelers, then feed again, causing localized outbreaks. Fortunately, the quality of medical care and housing available to most U.S. residents makes a large-scale reintroduction unlikely. Although prophylaxes aren’t 100% effective, malaria is preventable and treatable. A vaccine now exists for children.
Arboviruses and the bird biters
In the Northeast, the most dangerous mosquitoes live near us at high densities, feed multiple times, and prefer flying feathered prey, only taking advantage of slow, bare-skinned blood bags on occasion. Since birds are reservoirs for several arboviruses (ARthropod-BOrne VIRUSES), these mosquitoes are the most likely to infect us with a disease. In Maine, the arboviral risk to humans is generally highest in August and September since mosquitoes have had the summer to infect more birds and become infected.
Birds are reservoir hosts for serious mosquito-borne viruses like WNV and EEE. Sick and dead birds can signal an outbreak, but some infected birds appear unaffected.
The arboviruses of most concern are West Nile Virus and Eastern Equine Encephalitis (EEE). Both viruses reproduce in birds and can cause severe illness when transmitted to humans and horses. Researchers believe most infected people never display symptoms, but for individuals who develop encephalitis, permanent disability or death is typical. Young children and adults over 50 are most at risk.
Don’t forget the pet
Mosquitoes transmit heartworm, which kills thousands of dogs each year. A monthly pill can prevent the disgusting nematodes from nestling in our pups’ right ventricles. Though rarer, cats and ferrets can also get heartworms.
The battle plan
Step 1 – Don your armor
Choose a repellent that is registered with the EPA to prevent bites. DEET is an effective, low-risk repellent when used according to label directions. No product endorsement implied or intended.
Light-colored, long-sleeved clothing and a repellent containing 10-30% DEET should prevent most mosquito bites. DEET has been available to the public for over 50 years and is used by millions annually, with few reports of severe reactions. The Centers for Disease Control and Prevention and the American Academy of Pediatrics recommend using DEET to prevent arthropod-borne diseases in children older than two months. For individuals sensitive to DEET (and those who don’t like the smell or greasiness), products containing picaridin or IR3535 are effective alternatives. Oil of lemon eucalyptus can also repel mosquitoes for several hours but isn’t safe for children under three. When using repellents, always follow all label directions. Do not let children apply repellents themselves.
Step 2 – Destroy the nurseries
This bucket is full of springtails, but could easily breed mosquitoes. Dump out anything that holds standing water at least weekly.
Mosquitoes need standing water to multiply. Although we can’t do much about snowmelt pools and rain puddles, reducing the availability of stagnant water can curtail their population. Anything accessible to mosquitoes that holds water will breed them. Remember, some mosquitoes only need a bottlecap’s worth. So, remove the junk in the yard, turn it over, cover it, drill holes for drainage, or dump it out weekly. Tarps and other coverings should be tight, so they don’t sag and collect water. Change the water in kiddie pools, birdbaths, and pet bowls at least every week. Oh, and unclog the gutters.
Removing habitat used by adult mosquitoes won’t reduce their numbers much but can result in fewer bites. Adults need shaded, protected resting areas to shelter from the sun and avoid desiccation. So, keep the grass mowed and prune trees and bushes to let in as much sun and airflow as possible.
Neighborhood and community-wide management of larval habitat provides the best control. Plugged-up roadside ditches, stormwater basins, and urban wetlands create ideal mosquito breeding sites. Clearing them out makes them less favorable to larvae.
Step 3 – Employ technical superiority
Personal experience tells me mosquitoes will wait at the door until it opens, but if you’re getting bit indoors, repair any holes in window screens and seal any cracks to exclude more mosquitoes. Screens will prevent bites outdoors in small areas, like patios, porches, and gazebos, and mosquito nets for beds, hammocks, chairs, pack n’ plays, and strollers are available.
Propane-powered traps baited with carbon dioxide can catch a lot of mosquitoes but may not prevent bites. They’re not more attractive than a juicy, scantily clad human, so they must be placed between the mosquito source and the people to work.
Step 4 – Summon your allies(?)
Natural enemies are important, but efforts like adding bird boxes or dragonfly eggs probably won’t help a mosquito problem. Never release a non-native species unless you’re sure it’s legal to do so.
It doesn’t hurt to encourage the bats, birds, frogs, fish, and predatory insects that eat mosquitoes, but they’re unlikely to make a dent in the mosquito population. These animals usually target bigger and juicier insects. The western mosquitofish (Gambusia affinis) can control larvae in small ponds, but they should never be released where they aren’t native. They’re illegal in Maine because of their potential to become an invasive pest.
Step 5 – Chemical weapons
Larvicides applied to standing water can provide effective long-term control and come in lower-risk formulations like pellets, briquettes, and water-soluble pouches. Bacillus thuringiensis subspecies israelensis (Bti) is often the active ingredient of choice. It’s a bacterium that kills mosquito larvae by producing a toxin when they consume it. Bti only works on aquatic fly larvae; it doesn’t kill other insects. Unless the water body is confined to your property, individuals need approval from the DEP to apply any pesticide to aquatic sites in Maine, however.
While fogging and spraying for adult mosquitoes has become popular in recent years, except for public health emergencies, this should be the last resort. Government spray programs may reduce mosquito numbers, but the broad-spectrum chemicals often used to kill adults present safety and environmental concerns. And unless the problem mosquitoes are very short-ranging species, spraying for adults on individual properties won’t reduce mosquito abundance for long. These sprays may be helpful before an outdoor wedding or other important event but aren’t a sound long-term management strategy.
Beware of the snake oil peddlers!
Folklore and gimmicks abound around solving pest problems and circulate constantly on social media. Here are some enduring ones about mosquitoes.
Bug zappers – Though the crack of electricity as an insect meets its end might satisfy many of us, that’s about all bug zappers are good for. Yes, they attract insects, but they kill more predators of mosquitoes than mosquitoes themselves.
Ultrasonic devices – These appear to, if anything, attract mosquitoes.
Citronella candles and torches – Citronella oil repels some mosquitoes, but rarely more than a few inches from the candle or torch itself. The number needed to drive hungry mosquitoes from an area would be legion.
Mosquito plants – Similar issue. These plants contain repellent extracts, but that doesn’t mean they exude those chemicals in concentrations high enough to push mosquitoes from a patio.
This fresh-from-the-pack bug band is smelly but useless.
Bands, stickers, and patches – I’ve yet to find a valid study demonstrating that these repel mosquitoes from an appendage, never mind an entire person.
Eating a lot of garlic – Okay, this will make some of us repellent.
So, can we weather this weather?
In most years, Maine mosquito activity peaks in late June. So far, in 2023, they’ve shown no sign of slowing down. The torrents of rain, hideous humidity, and hellish heat have them in rare form. Unless the weather turns dry, we’ll have to wait until mid-September for a reprieve. And we aren’t the only part of the U.S. having a miserable mosquito year. This summer, we’ve seen a handful of folks with locally acquired malaria infections in Florida and Texas—for the first time in twenty years.
I’ve always loved the summer heat, but if it comes with a sopping side of mosquitoes, I’ll take a snowstorm any day.
Resources
Bernard, K.W. 2023. Category 7E Manual: Biting Fly and Other Arthropod Vectors Management. University of Maine Cooperative Extension.
Black flies are a fixture of springtime in Maine, so much so that they’ve been nicknamed the Maine state bird. We have more than 40 species! They swarm from our woodland streams and descend en masse to buzz around our heads, crawl into our orifices, and drink our blood.
Numerous black fly larvae anchored to rocks in a clean, well-oxygenated river. Photo courtesy of the National Park Service.
Description – Adults are small, robust, humpbacked flies. They have stubby antennae and a short, stout proboscis. Their color ranges from black to yellow. The aquatic larvae are shaped like bowling pins with one “leg” near their head on the underside. Tiny hooks on their hind ends help anchor them in flowing water. Most species bear two fanlike structures for filtering food from the current.
Distribution – Black flies inhabit every continent but Antarctica.
Habitat – Black flies need clean, moving water for their larvae. We find them in abundance near rivers, streams, and brooks. Since they can’t thrive in waters where dissolved organic matter is high or dissolved oxygen is low, their presence often signifies a healthy environment.
Life Cycle – Black flies have two different life cycles, depending on the species. Some overwinter as eggs, but most spend the winter as larvae. Females lay eggs in or near the water. After they hatch, larvae anchor themselves to rocks, logs, and other underwater objects by weaving a silk pad and hooking onto it. If the current doesn’t provide much to eat, they can let go and hope for better feeding grounds downstream. Because they breathe through their skin, they need highly oxygenated water to survive. When ready to pupate, most larvae build a silken cocoon underwater, usually in the spring after overwintering. Most adults emerge in April or May, riding an air bubble to the surface. Some species have multiple generations annually and produce biting adults throughout spring, summer, and early fall. I’m fortunate to live nearby a river that harbors one such species. Scientists have studied few black fly species in depth, but some appear entirely female, reproducing asexually.
Diet – Female black flies require blood to nourish their eggs, but like the males, they feed on nectar for their own energy. Some are opportunistic, biting whatever mammal or bird is available. Other black flies are picky, specializing in one group of animals or even one species. Simulium annulus, for example, targets loons. Some hunt humans voraciously, while others have no interest in us. A few species like us enough to circle our heads incessantly and try to burrow into our tear ducts, but rarely bite. The larvae feed on microorganisms, filtering them from the water using fanlike mouthparts.
Adult black flies have a short proboscis armed with serrated, scissor-like mandibles for slicing into flesh. Some species harass humans but don’t bite often. It took me ten minutes of standing still and getting pelted in the face by a hundred flies to get this picture.
Bites – While their antics and the welts they leave behind are maddening, blackflies aren’t the public health threat ticks and mosquitoes are–in the U.S. In some parts of the world, they cause tremendous misery through the diseases they transmit, river blindness being one of them. That’s not to say bites are harmless here. They tend to swell and bleed. A few hours with black flies leave some people looking like they just finished a bar brawl instead of a hike. How much and for how long depends on the person and previous exposure. Folks accustomed to them generally don’t react as much. Likewise, those first few bites at the beginning of the season often balloon up, but subsequent attacks leave milder welts. Sometimes individuals develop a sensitivity, however, and their reactions worsen as time goes on. And, while they’re not known to vector pathogens to humans in the U.S., they can still make us sick. When injected from numerous bites, their toxic saliva may cause fever, headaches, nausea, and swollen lymph nodes.
We don’t just have to worry about ourselves, either. Even up north, black flies can transmit disease to livestock and poultry. Occasionally, one hears a horror story in which the black flies are so thick that animals die via smothering, exsanguination, or toxic shock from their bites.
Battle Plan – Black flies are a byproduct of thriving streams and river restoration, so little opportunity exists to target them at their source without severely harming the environment. Bacillus thuringiensis var. israelensis, a bacterium that kills only mosquitoes, black flies, and similar species, is the only reasonable chemical option to control the larvae. Some states have regional control programs and apply Bti aerially. Maine doesn’t, and applications require a permit from the DEP unless the stream is contained entirely on one property.
Because females can fly miles seeking a blood meal, adult-killing sprays seldom provide control for longer than a couple of days.
Rather than trying to wipe them out, in Maine, the strategy with black flies is to discourage bites. Unfortunately, since they rely more on sight to target their victims, DEET and other insect repellents aren’t as effective against them as against mosquitoes. Avoidance and mechanical barriers will work better. Cover up, knowing black flies will crawl through any gap in clothing they can find in search of juicy flesh (they’ve figured out buttons), and dark colors attract them. A trick I learned from my dad is to coat a plastic sun helmet or hard hat in mineral oil. When the flies land on the helmet, they get stuck and suffocate. But I recommend a quality head net if the black flies are thick.
Black flies are annoying, but they’re the price of living, working, and playing alongside nature. The good news is that they don’t typically follow folks indoors and only bite during the day. They’re easy to shake if you have shelter.
When I was a young kid growing up in southern Maine, we rarely encountered ticks. Then the developments moved in, the no-hunting signs went up, and the deer took over. My mom has had Lyme disease four times now.
I escaped north, avoiding the people, deer, and ticks–for a while.
Last year, for the first time in the 13 years I’ve lived here, I saw deer sign on the property. They came in during the winter a few times to chew on my apple tree. I wouldn’t mind, except I was pretty sure I knew what would follow them.
I did.
In November, I discovered several ticks on the dogs, including one engorged with sweet, delicious pug blood. Since UMaine Extension’s Tick Lab is right across the hall from me, I had it tested. Sure enough, the sanguineous little parasite carried the Lyme bacterium. A few months later, the dog tested positive, too.
This year I found ticks before the snow had melted from the yard.
So, I’m conscripted to fight against the minute monsters. Having written about tick control and organized tick management programs, at least I’m ready for battle.
DESCRIPTION
Ticks are arachnids, so they’re eight-legged (except as larvae), antennae-less, and have a combined head and thorax region. The part of the tick that looks like its head, the capitulum, is its mouthparts.
Adult deer ticks (Ixodes scapularis) measure in at the size of a sesame seed. Females are two-toned, reddish brown, with a little dark brown shield on their backs. Males are uniformly dark. Nymphs are lighter colored and about the size of a poppy seed. If you see the six-legged larvae, congratulations on your preternatural eyesight.
DISTRIBUTION AND HABITAT
While particularly numerous in the northeast, deer ticks range throughout the eastern half of the U.S. and southern Canada. They have little trouble surviving Maine’s warming winters with adequate leaf litter. Dry summer heat, on the other, makes life tough for ticks. That’s why we find them less in the sunny lawn and more along the edge of the woods, amongst overgrown vegetation, and in piles of leaves. They need these cooler, moist, protected areas to avoid desiccation. So, deer ticks tend to stick to the shadows where they belong.
DIET
Blood. That’s it. Unlike mosquitoes, which at least have the decency to feed on detritus as larvae or nectar as males, all deer ticks need blood to molt to the next life stage. Females require extra to nourish their eggs. Deer ticks will feed on many mammal and bird species at any stage, but they have their preferences. The larvae mostly attach to rodents. Nymphs may seek larger prey, including rabbits, turkeys, robins, skunks, canines, and humans. The white-tailed deer is the ideal blood donor for adult deer ticks, but they’ll try to make do with any large mammal, including us, and small ones in a pinch.
Despite the myth that deer ticks leap out at us from the trees, they’re passive hunters. They can’t fly, jump, or even skitter. The deer tick holds onto the vegetation with its back legs and reaches out with its front ones, hoping we brush by so it can grab on–a behavior called questing. It would seem ridiculous if the loot wasn’t our blood. Once the successful tick hitches a ride, it often crawls upward, seeking penetrable flesh.
Using their barbed mouthparts, ticks puncture and anchor themselves in the skin. Swelling around the bite may make the tick appear to have burrowed in, but they only embed their feeding apparatus. Deer ticks feed for about a week if not removed. As they engorge with blood, females may quadruple in length. Their disgusting swollen abdomens pale, making them difficult to distinguish from engorged American dog ticks, a larger, less dangerous species.
LIFE CYCLE
The deer tick has a two-year, three-host life cycle. Yep, they’re not just gross and disease-vectoring–they’re needlessly complicated. In spring, females lay up to 3000 eggs among the dead leaves. The larvae hatch in late summer and usually snag a small mammal as their first host (and first opportunity to pick up the Lyme bacterium). After feeding, the larvae drop off and molt into nymphs. Nymphs lay low, spending the winter under leaves and other debris. They start questing for a second host in late spring or early summer of the following year. In Maine, peak nymph activity occurs around mid-July. Once they drop off the second host, nymphs molt into adults. Females must feed a third time to produce eggs, seeking a host (ideally a white-tailed deer) in the fall. Males may also quest in hopes of finding a mate on the host. If a female fails her autumn quest, she’ll get a second chance. Adults spend a another winter under the leaf litter. Any time temperatures rise above freezing, females that missed out in the fall will be on the hunt, but peak spring activity typically occurs in April.
The abdomen of an engorged female deer tick with eggs (left), adult female (top right), adult male (bottom right), nymph (center), and larva (bottom center). Photo by Jim Occi, BugPics, Bugwood.org.
BATTLE PLAN
Staying inside isn’t an option. Someone has got to do the yard work and take the dog out. The kids need to play in the fresh air. But most ticks are picked up in the backyard. So, what do we do?
Destroy their barracks. First, we can make our properties less hospitable to ticks. If there’s one thing humans excel at, it’s destroying habitat. Conveniently (for us, not wildlife), deer ticks suffer in the immaculate turf we’ve decided should surround our homes. Keeping the grass short, pruning low branches, removing fallen leaves, and cutting back brush make the yard less inviting to ticks. Areas people frequent, like the mailbox, swing set, picnic table, and hose hookup, should be trimmed short or surrounded by woodchips or gravel.
Target their allies. Rodents are not only tick nurseries but serve as the primary reservoirs for the pathogens that ticks vector. The fewer, the better when it comes to tick management. Remove the brush, rock piles, debris, and groundcover vegetation that harbor them. Clean up food and feed and keep garbage in rodent-proof containers.
Build a wall or moat. Hear me out. If you can exclude deer with a fence (it’ll have to be at least 6′ high), that should keep a lot of gravid female ticks off the property. A moat, okay, a strip (> 3 ft wide) of woodchips or gravel where the lawn meets woods, can keep ticks from moving out of the forest and serves as a visual cue to remind folks when they’re passing into tick habitat.
Don your armor. Wear long pants, socks, and closed-toed shoes when entering enemy territory. Tuck your pants into your socks and shirt into your pants. Choose light colors to make ticks easier to spot. Then spray clothes from the waist down with an EPA-registered insect repellent that lists ticks on the label. Products containing 20% DEET or higher are effective against ticks. Insect repellents containing picaridin, IR3535, and lemon oil of eucalyptus can also work. A better option is to wear permethrin-impregnated clothing. You can buy pre-treated clothing or treat clothes you own already, but never apply permethrin to your body. Whatever repellent you choose, read and follow the label directions.
Be vigilant for infiltrators. Ticks removed within 24 hours of attachment seldom infect their host with a disease. So end each day with a tick check, and if you find one, extract the atrocious arachnid immediately. You may have heard of using a matchhead, Vaseline, duct tape, gasoline, or the blood of a three-toed salamander to coax a tick to let go. As much as I love a good spell, don’t use witchcraft to convince a tick to detach. It won’t (but it might vomit into your wound). Use tweezers or a tick spoon.
Chemical warfare. Sometimes the health risks of a pest outweigh the health (and environmental) risks of pesticides. With greater than 40% of deer ticks carrying human pathogens in some areas, it’s no wonder many folks choose to treat their yards. Applications made by responsible licensed professionals provide the best and safest control. Treatments must target tick habitat, don’t hire a company that wants to spray the whole lawn. While some plant extracts can kill or repel ticks, they’re less effective than pyrethroids (the go-to synthetic chemicals for ticks). Botanical pesticides often break down quickly in the environment, requiring repeat applications for adequate control.
One low-risk strategy shown to reduce tick abundance is a spray of Metarhizium brunneum combinedwith tick control boxes. Metarhizium brunneum is an entomopathogenic (bug-infecting) fungus that kills ticks. It occurs naturally in the soil. Tick control boxes target ticks’ rodent hosts, luring them in with bait. But instead of poisoning the rodent, the box treats it with fipronil, the same pesticide found in many topical flea and tick preventatives for pets. It kills immature ticks on the host.
What am I going to do?
I’m not ready to spray the yard, but if tick abundance on my property climbs to levels I’ve seen farther south, I will. For now, mowing the lawn short will be the top priority. We’ll keep pushing the forest back, clearing vegetation. I’m working hard to remove the invasive plants established by the previous owner. With their dense growth habit, these species make prime tick habitat. I’ve surrounded the garden beds with gravel. Next, I want to get a mini electric woodchipper to shred every twig at the forest edge and create my moat. After having a fence relentlessly crushed by falling trees and moose, I think a wall is out. I need to do a better job with the leaves this fall.
We vaccinated the uninfected dog for Lyme. Both canines now take a chewable that kills ticks when they bite. I prefer using a permethrin-containing topical because it prevents ticks from hitching a ride, but permethrin is highly toxic to cats. And, of course, one of mine is extra sensitive to it. She almost died once from chewing on the dogs the day after I treated them. I still apply it to my boots and one outfit dedicated to yard work.
Every night, on days when my daughter or I venture beyond the lawn, I do a tick check. It’s been a hard habit to get into, but critical for anyone who resides alongside tick habitat. Like many folks, I’m anxiously awaiting the human Lyme vaccine, which is in trials now.
If you’d like to learn more about tick management and tick-borne disease prevention, see the excellent resources below.
Okay, these are far from monsters, though they can be annoying and true pests under the right circumstances. I’m covering them only because my local newspaper interviewed me about using pharmaceutical hydrogen peroxide to control them in houseplants. According to the internet, this household chemical is the latest cure for wilting plants. As someone who writes about pesticide safety for a living, these things make me cringe. It’s risky to make your own pesticides—and that’s what hydrogen peroxide becomes when you use it against a pest. Homemade pesticides haven’t been tested for safety or effectiveness and don’t come with any directions. Pesticides bought at your local garden center have undergone a rigorous registration process with the EPA and come with detailed instructions to help ensure they control the pest and don’t harm the plant, other property, humans, pets, or the environment. But pesticides often aren’t necessary at all. Not if we understand the pest well enough to disrupt its life cycle without chemicals.
Description. With their slender bodies and long limbs, adult fungus gnats resemble little mosquitoes. Depending on their family, they may have dusky wings or humped backs. Fungus gnat larvae are transparent-white, wormlike maggots with head capsules.
Fungus gnat larvae. Photo by Whitney Cranshaw, Colorado State University, Bugwood.org
Distribution and Habitat. Fungus gnat larvae live in the soil—wet soil. They inhabit it worldwide, especially in forests, where they’re harmless. They become pests only when they proliferate in over-mulched garden beds, greenhouses, mushroom farms, and houseplants. Adults usually stick close to larval habitat, running and hopping around atop the soil or nearby plants.
Diet. Fungus gnat larvae eat fungi and decaying organic matter. When numerous in wet soil, they may also feed on plant roots, causing damage. Although some flies with the gnat title bite, fungus gnats do not. Neither do the adults harm plants. They feed on nectar and are beneficial as pollinators.
Life Cycle. Under the right conditions, the fungus gnat can undergo its entire lifecycle in as few as 20 days. Females lay up to 200 eggs in the soil, where the larvae feed for about two weeks before pupating. After emerging, adults live for a week to 10 days.
Battle plan. Put the peroxide away. Chemical warfare is rarely necessary to manage household infestations of fungus gnats. Yes, we all want that secret trick to everything–that one little folk remedy that solves it. But most successful pest control takes a variety of sound management strategies. The most important one for fungus gnats is to reduce the breeding habitat, disrupting the life cycle. Wet soil high in organic matter, including the plant’s debris, will promote fungus gnat survival and reproduction. So, let the top few inches of soil dry out between waterings and ensure the pot has good drainage. Don’t add too much organic matter or let it accumulate. Consider repotting the plants in a sterile potting mix if the infestation is already out of control. Yellow sticky card traps can help to manage adult gnats and monitor the population. Prevent new infestations by keeping indoor plants indoors, inspecting new plants brought into the home, and repairing any holes in window screens.
Hydrogen Peroxide. Many pesticide products contain hydrogen peroxide, but most are disinfectants (disinfectants are pesticides). Few are labeled for use on plants or soil. Those that are, for the most part, treat plant pathogens. They can be a good choice because ready-to-use, dilute hydrogen peroxide products are relatively low risk and break down quickly in the environment. More concentrated products, however, can burn the skin, damage the eyes, irritate the lungs, and cause gastric distress. Highly concentrated products can kill. And hydrogen peroxide is a strong oxidizer, meaning it can cause explosions if improperly stored. For those who feel they must use a chemical, a soil drench of the biopesticide Bacillus thuringiensis var. israelensis (Bti) is a better choice for gnat control than pharmaceutical hydrogen peroxide. I don’t recommend any sprays for adults. The risks of treating indoor areas for a nuisance pest generally outweigh any benefits. Remember, fungus gnats can’t harm people or pets—but pesticides can.
K.W. Bernard 