This is an Aedes albopictus female mosquito obtaining a blood meal from a human host. Photo by James Gathany, Center for Disease Control and Prevention.

By Jeff Burbrink
Extension Educator Ag & Natural Resources, Purdue Extension LaGrange County

LAGRANGE — In Indiana, when it rains, you can count on a flush of mosquitoes a few days later. Mosquitoes need water to develop and we have had no shortage of water this spring.

Mosquitoes breed best in stagnant water, where they are protected from fish and other animals that will eat their larvae. Common breeding grounds include swampy areas, flood waters, woodland pools, slow flowing areas of lakes and streams and ditches where the aquatic growth slows the movement of water and protects the larvae. Mosquitos can also develop in tree cavities, old tires, rain barrels, gutters, flower pot saucers — in other words, just about anything that can hold water. I have seen several hundred mosquito larvae in just a cup of water!

Jeff Burbrink

Most of our mosquito species in Indiana lay eggs on the surface of water or in low places where water usually accumulates. Eggs hatch in less than three days after contact with water. The larva, also known as wrigglers, can mature in 7-10 days and then go into a cocoon stage, where they morph into an adult. Two or three days later, the adult mosquitoes emerge.

Only the females take a blood meal. Protein in animal blood is needed to produce the eggs. A typical female can lay 100-400 eggs. The male’s mate, and die fairly soon after emerging.

A mosquito’s body is about 90% water, so on a warm sunny day, they tend to hide in the shade, or their little bodies just evaporate. When the sun begins to set, the skeeters begin their search for blood. Removing rank vegetation from the edges of property can reduce resting places, but if you live near woodlands, you’re probably going to experience mosquitoes regardless of efforts to remove excess plant growth.

For personal protection, when possible, wear long-sleeved shirts and long pants with enough thickness to prevent mosquito mouth parts from reaching the skin. Dark colors attract mosquitoes, so wear light tones if you’re going to be outside. Mosquitoes are often most active at dawn and dusk. If possible, stay indoors or in a tightly screened area to avoid bites at these times.

Repellents are very useful in protecting against mosquito bites and are available under various trade names. Those that contain the active ingredient diethyl toluamide  are the most effective. Only use repellents that are registered by the Environmental Protection Agency. These are proven to be effective when used according to label directions. For concern about products for use on children, choose those products that indicate on their labels that they are safe for use on children.

Citronella candles are popular, but may be of limited effectiveness because of outdoor wind movement. A granular repellent containing napthalene compounds can be applied on lawns and other mosquito-infested areas. It effectively keeps mosquitoes repelled for several hours, but you have to put up with the smell of mothballs.

Mosquitoes can transmit diseases to humans and some animals. Mosquitoes may transmit West Nile Virus to dogs, cats, horses and humans or heartworms to dogs. We had a major outbreak of Eastern Equine Encephalitis a few years ago, which killed many horses and a few people in northern Indiana and southern Michigan. An EEE vaccine is available for horses, but it must be administered annually to be effective.

During times of high infestations, keep pets inside the house, a screened-in kennel or porch area. Avoid walking your pet during prime mosquito “feeding time.” Check with a veterinarian for preventative measures and symptoms to look for.

If you live in a mosquito infested area, it might be wise to coordinate efforts within a neighborhood. For example, if you make extra efforts to limit mosquitoes on your three-acre lot in the middle of a 150-acre wooded area, the effectiveness will be minimal because the skeeters will simply fly in from next door.

Purdue has publications on controlling mosquitos.