There are more 4,500 species of fruit flies in the world. The genus Drosophila includes a large number of species of fruit flies belonging to the family Drosophilidae. Among these species, D. melanogaster Meigen (referred to as red-eyed fruit fly) and D. repleta Wollaston (referred to as dark-eyed fruit) are considered the most common species of fruit flies found inside structures. Fruit flies are small, about 1/8-inch long, and have transverse black rings across their abdomen. Red- and dark-eyed fruit flies look mostly identical, except the adults of the dark-eyed fruit flies are a little larger in appearance than red-eyed fruit flies.
Fruit flies are pesky bugs that pose a challenge to PMPs. Dark-eyed fruit flies are the most common species in restaurants and commercial buildings, while red-eyed fruit flies are usually encountered in homes. They may coexist anywhere with decaying organic matter that match their expectations of taste and flavor — the larvae of red-eyed fruit flies prefer to breed in relatively new or mild decayed organic matter; dark-eyed fruit fly larvae like old decayed organic matter. Due to their short life cycle and the large mass of eggs they produce (up to 500) fruit flies can be a problem year-round, especially in restaurants where sanitation is an issue. In order to meet your customers’ expectations, below are five tips for fighting fruit flies.
1. Find/eliminate breeding sources. At every service visit, carefully look for areas of fermenting or decaying organic matter. Some of these areas include where fruits or vegetables are stored outside of refrigerators/coolers; in seldom used, emptied or cleaned recycling bins; in the film of debris that naturally accumulates in pipes, traps, sinks and drains; where the legs or feet of appliances, tables or cabinets touch the floor; in empty tomato, ketchup, fruit and vegetable bottles stored in basements; in empty bottles or cans of vinegar, wine, cider and beer; under floor mats; near dirty dried mops or brooms; in cracks and voids behind liquor bars; and in any leaking pipe or standing water. Outdoors, search nearby dumpsters, garbage cans or in damp compost piles where fruits and vegetables are discarded.
2. Partner with your customer. Once breeding sources are identified, they need to be removed. To do so, build a strong partnership with your customer. Establishing successful partnerships with your customers may take time. But it’s important to create the right framework from the start by properly and regularly communicating to the customer your findings, and all corrective and preventive measures that need to be taken. During discussions with the customer and on your report, set realistic treatment expectations and clearly defined responsibilities by creating an outline that classifies and prioritizes duties.
3. Apply proven insecticides. Sanitation is key to preventing a fruit fly infestation. However, sanitation practices require time to provide total elimination of fruit flies. Implementing good sanitation routines can be a challenge. While sanitation takes its course, apply proven insecticides to provide temporary relief. If a pesticide application is needed, use a proven residual insecticide to treat fly- resting areas as well as larvae-breeding areas as approved by the product’s label. Examples of resting places are floors, walls, ceilings and other surfaces near fruit flies’ breeding areas or around light sources. Never treat places where human, food, water or food contact surfaces can be exposed. Carefully apply limited crack, crevice and spot treatments to areas under appliances, under floor mats, around dumpsters, around ceramic tile, windows, doors, grout joints, etc. For large infestations, apply space treatments using proven aerosols to knock down exposed adult fruit flies. Prior to a space application, make sure to remove or cover all food items and food contact surfaces (e.g., equipment, benches, shelves — areas where exposed food may be handled, held, prepared, processed or served). If left uncovered, these areas must be thoroughly cleaned by a method capable of removing chemical residues after treatment. In areas frequently exposed to accumulations of moist organic matter — such as commercial floor drains, garbage disposals, under and behind heavy appliances, around garbage storage areas — it is recommended to use a proven microbial product that eats away grease, food debris and other wastes (larvae food) or use borate dust. Let your customer know that using bleach in these areas will deter the bio-product being used in the cleaning. Repeat applications at two- to four-week intervals depending upon the severity of infestation. (Borates may kill bio cleaning agents. Therefore, you can choose either one of these options, but not both.)
4. Reactive vs. proactive. Recommend to your client the following actions: regular cleaning of food debris; taking garbage out daily; buying only needed fruit and vegetable items and storing them inside the refrigerator or in sealed containers, when applicable; making sure all windows and doors have screens (and that those screens are in great condition). These are only a few examples for keeping fruit flies at bay. Use insect light traps (ILTs) indoors to monitor newly emerged adult fruit flies so you can manage fruit flies early before a large infestation is established in the location.
5. Persistence takes time. Dur-ing your service visit, evaluate inspection and monitoring data to determine if further actions are needed. Do not forget to communicate any changes to all parties involved. Never give up! Persistence and finding and removing all fruit fly breeding sources is important in achieving success.
IN CONCLUSION. Fruit fly management requires chemical and non-chemical control methods to remove larvae-breeding sources. Build rapport with customers by communicating and documenting all corrective actions taken and inspection findings, including entry points, sanitation and all breeding places. Be sure to include photos of all conducive conditions and attach them to your report.
The author is technical and training director for Adam’s Pest Control, Medina, Minn.