June 5, 2003 at 2:55 p.m.
Mosquitoes are insects belonging to the order Diptera, the tree flies. Like all Trueflies, they have two wings, but unlike other flies, mosquito wings have scales. Female mosquito's mouth parts form a long piercing-sucking proboscis. Males differ from females by having feathering antennae and mouthparts not suitable for piercing skin. A mosquito's principal food is nectar or similar sugar source. Mosquitoes can be an annoying, serious problem. They interfere with work and spoil hours of leisure time. They attach on farm animals and can cause loss of weight and decreased milk production. Some mosquitoes are capable of transmitting diseases such as malaria, yellow fever, dengue filariasis, several kinds of encephalitis, and west nile virus, to humans and animals.
The mosquito goes through four separate and distinct stages of its life cycle. They are the egg, larvae, pupae, and adult. Each of these stages can be easily recognized by its special appearance. Eggs are laid one at a time or attached together to form rafts that float on the surface of the water. Most eggs hatch into larvae within 48 hours, while others might withstand sub-zero winters before hatching. Water is a necessary part of their habitat. The larvae lives in the water and comes to the surface to breathe. Larvae shed their skins four times, growing larger after each molt. Most have siphon tubes for breathing and hang upside down from the water surface. The larvae feed on microorganisms and organic matter in the water. During the fourth molt the larvae changes into a pupa.
The pupal stage is a resting, non-feeding stage of development, but pupae are mobile, responding to light changes and move with a flip of their tails towards the bottom or protective areas. This is the time the mosquito changes into an adult. When development is complete, the pupal skin splits and the adult mosquito emerges.
The newly emerged adult rests on the surface of the water for a short time to allow itself to dry and all its body parts to harden. The wings have to spread out and dry properly before it can fly. Blood feeding and mating does not occur for a couple of days after the adults emerge.
There are over 2,500 different species of mosquitoes throughout the world with about 200 species in the United States. Only the female mosquito requires a blood meal and they bite animals and birds, warm or cold-blooded. Stimuli that influence biting include a combination of carbon dioxide, temperature, moisture, smell, color, and movement. Females prefer horses, cattle, smaller mammals and birds, and humans as a lesser choice.
Control of the mosquito this year can be quite a challenge, but there are some things that will help:
1. Destroy or dispose of tin cans, old tires, buckets, unused plastic swimming pools, saucers or flowerpots, etc.
2. Change water in birdbaths and wading pools, ornamental pools, etc., at least once a week.
3. In other words, wherever there is standing water eliminate if possible.
If you need to use a repellent, here are some common sense rules to follow:
1. Avoid applying high-concentrations (30 percent DEET) products to the skin, particularly of children.
2. Pregnant and nursing women should minimize use of repellents.
3. Never use repellents on wounds or irritated skin.
4. Apply repellents sparingly only to exposed skin or clothing.
5. Keep repellents away from eyes, nostrils and lips.
6. Do not inhale or ingest repellents or get them in eyes.
Chisago County is not part of the metro mosquito control district and there are currently no organized local control efforts. Some townships are looking into what it would cost to have a local program.
The Master Gardeners have a variety of native plants and heirloom tomato plants for sale at the Extension Office. They will also be having a plant sale at the office on Saturday, June 21 in conjunction with North Branch Midsummer Day Festival.
For more information on the U of M Extension Service web page go to www.extension.umn.edu and search. Or, you may call our Yard and Garden Line anytime and leave a message at (612) 624-4771. A Master Gardener will return your call. The Master Gardeners also staff the Extension Office on Monday from 4:30 to 8 p.m. Call (651) 674-4417 or drop in with your samples and gardening questions.