Plants that bite


With a name like Buffalo Gnat, one would expect a large hairy, hump-backed insect that travels in a large herd. Instead what we have invading the entire Midwest this spring is a small insect (also called black fly) the size of a fruit fly or smaller. So what is the problem?

The problem began this spring with continual cold, wet weather that started in April and continued into June. These conditions proved to be perfect for the breeding and hatching of the Buffalo Gnats. They spawn in wet areas near fast-moving water. The more rain we have, the more gnats hatch.

Every spring we see varying populations which are the first buggers to appear followed by pesky mosquitoes that favor warmer weather. Generally, there are one or two life cycles of gnats in the spring, but this year it appears there have been multiple generations with a high population each time, resulting in swarms everywhere. The good news is that the gnat larvae are very sensitive to warm water temperatures. Once the water temperature reaches 66 to 75 degrees and the sun comes out bringing drier weather conditions with the summer season, the larvae will die and the gnat season will be over until next spring.

The Buffalo Gnats, or black flies, are blood-sucking flies of the Simuliidae family. The females will bite animals and people for a rich, red meal that is needed for egg production. Gnats will fly up to 10 miles in search of a meal. Large numbers of gnats have attacked poultry and livestock, causing stress and even death. We have had reports in the Clinton area in the past of poultry dying from these high populations of gnats due to anaphylactic shock, toxemia, blood loss or suffocation when the flies are inhaled.

Bites to people can be irritating like a mosquito bite and can cause painful welts needing medical attention in people who are allergic to them. Since the insects are daytime feeders, the best protection is avoidance. If you must be outside, wear light-colored clothes with long sleeves. Treat clothing with Permethrin or use insect repellants containing DEET. Home remedy controls which are more earth friendly are vanilla, sage, Avon’s Skin So Soft and, believe it or not, a fan turned on HIGH! Bug Soother is a newer remedy and can be found at local stores.

Another tiny critter that can really irritate us is the chigger. Chiggers as we know them are actually larvae of harvest or scrub mites. Mites are not classified as insects; they are in a class of their own, so many of the insect sprays we use are not effective against chiggers or mites. There are three stages in the life cycle of this pest: eggs hatch into larvae, which turn into nymphs, which turn into adults. The adults and nymphs feed on plant material. The larvae, however, jump onto animals or bare feet as we walk through the grass. Being only 1/50th of an inch, they ride on our skin unnoticed. Then they will attach to a hair follicle or skin pore and secrete an enzyme. This enzyme ruptures skin cells and they drink this fluid. The enzyme is what can cause the skin irritation and itching. Chiggers like to migrate to skin underneath tight clothing, such as socks and waistbands. The good news is that in the Midwest chiggers don’t spread any diseases, but the bites can get infected from scratching. Chiggers like damp areas with lots of vegetation, so as the summer gets warmer and drier this mite population declines.

Margo Hansen is the horticulturalist and Director of Programs at Bickelhaupt Arboretum.