Aerial Assault

By Andrea Putnam | June 2, 2005
From Missouri Conservationist: Jun 2005

Pull on your long pants, put on a long sleeved shirt and douse yourself in bug spray. We are entering the bug season.

As summer approaches, we find ourselves preparing for a relentless aerial assault of flying insects. Pesky battalions of bugs take aim at our skin, causing fear and fury, as well as irritation and discomfort.

Mosquitoes, horseflies and midges are among the many annoying pests we encounter when we venture outdoors. The best defense against having our summer days spoiled by these insects is to learn their behaviors and habitats—and what you can do to avoid getting bit.


Mosquitoes are on everyone's not-very-nice list. These small, flying insects are actually a type of fly. Mosquitoes normally feed on plant nectar, but the females need a blood meal before they can lay fertile eggs. The females are alerted to potential blood donors primarily by movement, heat, odor and exhaled carbon dioxide.

When a female mosquito finds a victim, she pierces its skin with her long, thin proboscis—or nose. The female's saliva eases penetration and keeps the victim's blood from clotting. She draws blood out as if through a straw, filling her abdomen. If you watch, you can see her abdomen become reddish as she feeds. Males have smaller mouthparts and aren't able to bite.

Missouri is home to about 50 different species of mosquito, but all of them have similar life cycles, developing through egg, larva, pupa and adult. The egg, larval and pupal stages are spent in pools of standing water before an adult mosquito emerges.

Most mosquitoes only live a few weeks as adults, so you'll experience several generations through a Missouri summer. Some mosquitoes survive through winter as adults, eggs or larvae.

A mosquito bite results in a wheal, a small swelling mound, that itches. The swelling and the itchiness persist until our immune system breaks down proteins in the mosquito's saliva.

Worldwide, mosquitoes are a major transmitter of diseases, including malaria, yellow and dengue fever and encephalitis. They also transmit diseases to dogs, birds, horses and other animals.

When mosquitoes are annoying us, it's hard to think of them as beneficial, but mosquitoes do pollinate flowers and provide food for bats, turtles, fish and birds.

It's still okay to swat them, though.

Horse and Deer Flies

The bite of these pesky critters can make you feel like you've been kicked by a horse. As is the case with mosquitoes, only the females seek blood. Males drink plant liquids, such nectar or honeydew.

Horse flies are usually bigger than deer flies, which are slightly larger than house flies. Horse fly wings are clear, while deer fly wings have dark markings or patterns. As their name suggests, horse flies usually attack livestock. People apparently make a good target for deer flies, especially on or near streams or at the beach.

The bite of these flies is very surgical. The fly's mouthparts act like scissors and a sponge. After cutting the skin, the female fly soaks up blood, which flows more freely because of anti-clotting proteins in their saliva.

The airborne attack of horse flies occurs around Missouri's rivers, lakes and streams, which are prime breeding habitat.

Horse and deer flies usually lay their eggs on vegetation near water. After the eggs hatch, the larvae feed on almost anything organic they can find in muddy soil. They may remain in the larval stage through winter or, in the case of some species, as long as three years before maturing. The flies are usually abundant for only a month during the summer. Deer flies peak and decline before horse flies.

As is the case with any biting insect, deer and horse flies can spread disease. They are even suspected of transmitting Lyme disease.

These flies, especially in the larval stage are an important food sources for frogs, turtles, fish and birds. On the other hand, they are absolutely irritating when they buzz around the head and shoulders area. Good luck trying to slap them; they are agile and elusive.

Midges and Gnats

The clouds of insects, usually called midges or gnats, that you sometimes see and walk through have the unique ability to annoy without biting. These tiny flies bombard your face when you're hiking or bicycling. During their mating season, clouds of midges seem to hang in the air.

Most midges do not bite or pierce the skin of humans, but they seem to home in on body cavities when you walk into the cloud. They produce high-pitched buzzing sounds in our ears and irritate our noses and eyes.

Midges feed on live or dead vegetation and seem to follow moisture. They complete their life cycle in wet areas and often show up after a few days of wet weather. Some species also seem to be attracted by lights. Midge numbers decline following dry spells.

These insects are a staple in many animals' diets including fish, turtles, frogs and birds. Sometimes people accidentally swallow them, too.

Venture Forth

Don't let a few gazillion pesky insects keep you from Missouri's wonderful outdoor recreational opportunities.

Defend yourself against aerial assault by wearing long pants and long-sleeved shirts when outdoors. You can keep deer flies from their favorite perch—the top of your head—with a hat. If you expect the bugs to be extra bad, wear a mesh head net or even a mesh body suit. Use mosquito nets or similar netting around your picnic table and sitting areas (away from fires) when camping.

Most insect repellents contain diethyl-toulamide (DEET) in concentrations that range from less than 5 percent to 100 percent. The stronger the concentration, the longer it will keep insects from biting you.

DEET can cause blisters, clogged or runny noses, shortness of breath, reddened and tingling skin or other serious reactions in some people. Use the lowest concentration that will work and apply it sparingly in well-ventilated areas. Use 10 percent or less DEET on children. Use small amounts of repellent and keep it away from eyes, mouth, nose, open cuts and sores and food.

Natural repellents usually contain some combination of essential oils, such as citronella, eucalyptus, lavender or soy. They keep insects from biting, but only for a short time, so you need to reapply them often.

Generally you can make yourself less attractive to biting insects by not wearing perfumes or scented lotions. Insects are attracted to shiny objects, so leave your jewelry at home. Light, earth-toned clothing is probably your best choice for clothing. Dark colors attract flying insects, such as deer flies.

Reduce mosquito numbers on your property by eliminating standing water in flowerpots, buckets or other water-collecting containers around your home. Change the water in your bird bath weekly. This eliminates breeding habitat for flying insects.

Do not over-water your lawn. Immature gnats and midges can develop in moist or wet soil. Keep your lawn cut short so adult mosquitoes cannot hide in it. Stock ornamental ponds with fish that eat mosquito larvae.

Chemical treatments, in most cases, are only a temporary fix to your insect problem. Most applications only kill the insects that they come in contact with. Covering exposed skin or protecting it with repellents and eliminating breeding habitat are the most effective ways of dealing with summer's aerial assault of insects.

This Issue's Staff

Editor - TomCwynar
Managing Editor - Nichole LeClair
Art Editor - Ara Clark
Artist - Dave Besenger
Artist - Mark Raithel
Photographer - Jim Rathert
Photographer - Cliff White
Staff Writer - Jim Low
Staff Writer - Joan McKee
Circulation - Laura Scheuler