[Annual Fly Control Issue] What’s New in Fly Control?

Dr. Philip Koehler, professor of urban entomology, University of Florida, Gainesville, says small flies, including phorid, drosophila and drain flies cause the most problems in most places. “I call them terrorists,” he stated. And when discussing large filth flies, such as flesh flies, blow and bottle flies, and house flies, Koehler usually refers to them as invaders. “Fly control is one of the most important problems the pest control industry deals with, especially in the summer,” he emphasized.

Koehler and two members of his University of Florida research team, John Cooksey and Casey Parker, recently have done considerable research on that subject and learned important facts about insect light traps (ILTs) and baits. They imparted that information to attendants at the NPMA’s annual PestWorld in Phoenix last October.

“Small flies are a serious threat to public health and breed within a structure, so you must find the breeding sources to provide long-lasting control,” he maintained. “Large filth flies usually breed outdoors but will invade a structure through gaps, cracks and crevices, as well as through improperly screened doors and windows.

“These species are all attracted to light and also to sugar-based baits,” he said. “They need the energy from sugar in order to fly.”
 

ILTs.

Research in 1983 on the sensitivity of fly eyes found there are two sensors present that dictate what a fly will do in response to light. As such, using ILTs, especially in commercial accounts, is a prime method of control, according to Koehler. “But you’ve got to place them properly so outside flies cannot see them (you don’t want to attract flies from outside into the facility) and you should locate them near indoor odor sources as well. They should operate 24 hours a day, too. Lots of ILTs are needed in some accounts and ought to be placed no further than 20 to 25 feet apart,” he suggested.

Cooksey, after researching the subject, concluded that 13-month-old UV bulbs catch about 80 to 90 percent as many flies as new bulbs. The usual recommendation from bulb manufacturers is that their ultraviolet bulbs, which degrade over time, be changed yearly and possibly twice a year. Cooksey’s research suggests that bulbs may not have to be changed quite that often.
 

Fly Baits.

On the subject of baits, Koehler said house flies have evolved resistance to many classes of fly bait insecticides. “The house fly showed resistance to DDT before any other insects did. It has a tremendous capacity to quickly evolve resistance to pyrethroids, carbamates and nicotinoids. So constant use of one product results in failures. The solution? Rotate the use of insecticide classes. You only have two right now — carbamates, which are cholinesterase inhibitors, and nicotinoids, acetylcholine receptors.

“However, it would be good to have a third class of chemistry for better rotation,” he stated. “Fairly soon there will be a third class available for fly baits, which will be the first fly bait to be listed by the EPA as ‘reduced risk.’ It’s very specific for certain pests, and its mode of action causes muscle paralysis.”

Research assistant Casey Parker evaluated that new class of chemical for effective fly control during the summer of 2013.

She discussed the field study conducted at several horse farms, one in Ocala, Fla., and the other in Gainesville, Fla. “We took baits and stuffed them into screen bags and placed sticky cards to monitor the flies and give them surfaces to land on.

“We also did a bait treatment at the horse farm to look at the amount of flies killed by baits as well as the population reduction they were causing,” she said. “We did the treatment at areas where flies were congregating, such as breedways, feed rooms, and horse stalls. At various time intervals we counted the dead flies and came back again and counted again.”

The results she reported indicated that after two hours there were 2.8 more flies killed by the Zyrox bait, compared to the carbamate. And the Zyrox bait reduced the population by 55 percent one hour after the bait placement, compared to no reduction produced by the Golden Malrin. After two hours the new bait reduced the population by 78 percent, compared to a 38 percent reduction by the carbamate.

Based on UF’s research on the new fly chemistry, Koehler recommends a three-way rotation program for fly baiting: “Treat with a (with the new product), follow it with a carbamate, then with a nicotinoid, then go back and repeat the rotation. That should delay the onset of resistance.”

The author is a freelance writer based in Milwaukee. Email him at jfox@giemedia.com.