A. It's hard to tell for sure, but your description sounds like black flies, said entomologist Jeffrey Hahn of the University of Minnesota's Yard and Garden Clinic.
Black flies, also called gnats, are common and a nuisance in summer, generally in the morning, evening and on cloudy days.
Vanilla extract works well to repel gnats. Apply it around the head, especially on a head band. The extract has to be re-applied every 20 to 30 minutes.
The commercial product Buggspray Vanilla is available at many drug and sporting goods stores.
Gnat nuisances diminish as fall settles in.
July 3, 2002 - ABC News and the New England Journal of Medicine
The results? On average, most of the skin softeners provided less than 10 minutes of protection. The plant-based citronella products offered about 20 minutes of protection. Repellents containing the chemical N,-N diethyl-m-toluamide, better known as DEET, were by far the longest lasting.
A 7 percent DEET solution provided almost two hours of protection. A 24 percent solution lasted more than five hours.
A. "Electric bug zappers kill mosquitoes, but they also kill other beneficial insects, said Jim Stark of the Metropolitan Mosquito Control District.
The zapper's effectiveness at reducing mosquito numbers in a backyard is questionable, he said. Use of a zapper may actually increase the mosquito nuisance by attracting them to your backyard, where they are distracted by other cues that draw them to humans. That includes body heat and carbon dioxide in exhaled breath.
The mosquito trap or magnet uses a compound that mimics human or animal respiration. Mosquitoes attracted to the bait are trapped in a container or sack. Typically, the bag of collected mosquitoes is put into the freezer until they die and is then discarded, Stark said.
He said the trapping units, costing $800 to $1,200, also attract mosquitoes to the yard. Stark said he's not seen any field tests on the trap's effectiveness at reducing the number of mosquitoes.
Larval-control products, used properly, can control larval mosquitoes in small areas for up to a month, he said. The most common larvicide available for home use is Bti (bacillus thuringeinsis israelensis). Marketed as mosquito dunkers, doughnuts or bagels, these products are usually pressed into round briquettes 2 to 3 inches wide.
Bti-based products are effective at controlling mosquito larvae in standing water and are recommended for limited use on small areas.
Bti, naturally occurring bacteria, are found in soil, and are very specific to mosquitoes, biting gnats and a few closely related flies. Bti acts on the unique digestive system of mosquitoes. It is not hazardous to people, pets, wildlife or the environment.
The chief drawback is cost. A Bti doughnut costs around $2 and is designed to treat a 10-by 10-foot area for 30 days.
Although Bti is safe and effective (85 to 95 percent of larvae will not develop into adults), you must treat large areas to notice a difference. If you are treating only your immediate area, mosquitoes from untreated areas will still annoy you. Some species of mosquitoes travel 15 miles from their hatching area.
Bti is available commercially at Summit Chemical, 1-800-227-8664. It's also sold under the name Mosquito Dunks and Bti Briquets at hardware and home and garden stores.
To protect yourself from mosquitoes, avoid being outdoors during pre-dawn and pre-dusk, Stark said. Cover up as much as possible and wear insect repellent containing DEET. Be sure DEET repellent used on children is designed for children."