AMES, Iowa -- Biting bugs are causing lots of complaints as Iowans begin spending more time outdoors enjoying the mild weather. Ken Holscher, Iowa State University Extension entomologist, says seasonal complaints about ticks and chiggers are at normal levels this year, but 2009 seems to be a banner year for black flies, small gnat-like insects that depend on feeding on the blood of other animals to perpetuate their life cycle.
Holscher said the prolonged rainy season and flooding in the spring and summer of 2008 may be partially responsible for large black fly populations this year. Black flies lay their eggs in flowing water, and the larvae develop into adults over two seasons. So the heavy water flows of 2008 and the wet spring this year may be contributing to the 2009 infestation.
Unlike mosquitoes, which develop in still water, black flies cannot be controlled easily by insecticides. The biting black flies are adult females who need a meal of blood before they lay eggs, and their active season is from early May to mid-June. Holscher said they should disappear in another two or three weeks.
Two other biting pests, ticks and chiggers, also are topics for questions that Holscher receives at this time of year. Tick activity begins when spring arrives and continues through the summer and into the fall, and ticks feed on warm-blooded animals in the larval, nymph and adult stages.
Holscher said ticks are opportunists who depend on the proximity of animals for their meals. “Ticks don’t find people – people find ticks,” he said, explaining that they are not actively moving around in their habitat, but usually stay in one location in tall grasses or wooded areas and wait until a meal comes to them.
Another misconception is that ticks use trees as a way to hitch a ride on people. Ticks nearly always live at ground level, in areas that have humidity of 75 percent or more. Holscher said when they sense a meal moving into their territory, through indicators such as ground vibrations or the carbon dioxide emitted by the animal, they move into position on grass blades and other plants where they can easily latch on to the animal as it brushes by.
People afflicted by ticks almost always pick them up at ground level. They are frequently found in the hair and on the head, and Holscher says that is because they have worked their way up the body looking for a comfortable place to attach for a feeding.
Ticks have large mouth parts and it can take a full day to attach themselves to the skin so they can begin a feeding. Often the victim will not feel the bite and will not notice the tick for up to 24 hours. Tick bites on humans come from adult females who feed during a 10- to 14-day period. If there also are males in the area, they are attracted to the females, and at the end of the feeding the female will detach herself from the host and deposit her eggs to launch the next generation of ticks.
If you are bitten by a tick, the best way to detach it is to pull it out with slow steady pressure using tweezers or forceps. Holscher said victims should never apply heat to the tick or any foreign materials such as fingernail polish or flammable fluids, because those solutions will stimulate the tick to produce more saliva which can cause more irritation to the site of the bite.
Ticks cannot survive in dry sunny areas, Holscher said, so keeping lawns mowed and vegetation trimmed can help control them. If an open area adjoins a tall grass area such as a roadway ditch or a woodland, sometimes treatment with an insecticide along the border of the tick habitat will help.
People who spend time in tick habitats for recreation or work reasons can protect themselves by dressing appropriately, including long pants tucked inside boots or socks. Masking tape wrapped around the bottom of your pants leg with the sticky side out also will help keep ticks from migrating up your body to open skin.
Holscher also frequently receives inquiries about chigger bites. Chiggers are the larval stage of mites and are found in the same habitats as ticks. They are too small to see, but when they find a host animal, they will attach themselves to hair shafts, follow the shaft to its base, and feed on the contents of the hair follicle. They do not burrow into the skin, but they inject saliva into the cells they are feeding on, which will eventually make the cell burst, causing irritation. As with ticks, the best way to avoid chigger bites is to avoid areas where they reside.
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