[Annual Fly Control Issue] Fly 411

Flies are of the order Diptera and are divided into beneficial and deleterious subgroups. The harmful species are what people are concerned about. Agricultural pests include species such as cluster flies, face flies and horn flies. Health pests include species of mosquitoes (malaria mosquitoes are the No. 1 worldwide pest), deer and horse flies, and the common house fly. Other species such as crane flies are harmless but are a nuisance — their large size frightens people. Last but not least are the small flies, such as drain and fruit flies.

Fly control in residential accounts must incorporate an Integrated Pest Management approach and the PCO’s use of a systematic approach to controlling flies. Furthermore, residential issues are not always one-dimensional in nature. For example, mulch and grass clippings are not always the source of breeding populations in residential accounts. Livestock barns and pens, which contain bedding materials and manure, are more often the source of fly problems. Many flies entering homes originate from such livestock sites. In addition, flies can continue to develop during colder months in milk barns, hog houses or confined feeding units that are closed and warm. Sometimes, pest management professionals ignore this variable.

Overall, good sanitation is the basic step in all fly management. However, pest professionals also need to understand the desired environmental conditions, life cycle and nutrient preferences of the pest species in question. Knowledge of these biological aspects in conjunction with using an IPM approach, including insecticidal, biological, and augmentation and cultural practices, will help the PCO to develop the protocol that yields the best possible results. Consideration of all of these components and their mutual relationships and influences will dictate the PCO’s approach in developing the most efficacious methods for controlling pest fly populations.

NECESSARY CONDITIONS? Understanding environmental conditions for breeding in relation to controlling pest populations is the first priority, because individual fly species need specific environmental conditions for growth and development. Elimination of breeding areas is necessary for good management. Contrary to belief, flies do not choose breeding sites and nutrient sites randomly, but rather are drawn to specific breeding and resource sites.

For example, the house fly, Musca domestica Linnaeus, is a well known cosmopolitan pest of both farms and homes. This species is always found in association with humans. It is the most common species found on hog and poultry farms, horse stables and ranches, and it can also breed in clean wet environments, which adds to its adaptability. Mosquitoes need standing water. Horseflies need vegetation. Drain flies need the organic matter that accumulates in drain and sewer pipes. Horn flies that attack cattle require feces. Cluster flies, which are found in homes, churches, hospitals, apartment complexes, commercial and public buildings, and other structures, require soil cracks and crevices offering access to earthworms. Hence, each species requires specific environmental conditions. In fighting flies, food and materials on which the flies can lay their eggs must be removed, destroyed as a breeding medium or isolated from the egg-laying adult.

Since the house fly can complete its life cycle within 10 days, removal of necessary substrates at least twice a week is necessary to break the breeding cycle. Garbage cans and Dumpsters should have proper lids and be cleaned regularly. Dry garbage and trash should be placed in plastic garbage bags and sealed properly. All garbage receptacles should be located as far from building entrances as possible. The farther away receptacles are located, the less the chance of fly intrusion.

OTHER CONSIDERATIONS. One must also understand the life cycle of flies. How long do adults last? How often are eggs laid? What is the development site of the larva for the species in question? For example, horse and deer fly larva prefer different conditions. The larvae of horseflies are found in somewhat drier substrates and have a wider distribution compared to deerflies, whose larvae are found in substrates with relatively high water content. House fly larva prefer a variety of organic materials such as manure, garbage, sewage, food wastes, lawn clippings, septic tanks and silage.

Most fly larvae will search for required nutrients as well. I have witnessed house fly larvae pupate under a clean damp towel. Remove the towel and the larvae crawl with conviction to look for another suitable resting place with the proper environmental conditions for eventual pupation and adult emergence.

Another tool for the PCO in controlling pest populations is augmentation of environmental conditions. The major fly breeding areas at feedlots and dairies are found around bunks where feed spills over and in debris basins that do not drain properly. Proper drainage can prevent accumulation of standing organic matter. Screening windows and doors helps prevent flies from intruding into households. In addition, screening windows and doors helps keep flies out of barns and chicken and pig parlors as well. Sticky traps at fly entrance points help reduce the number of flies getting into buildings. Remember, air or water can be used for agitation and to make potential egg laying sites less palatable.

INSECTICIDE USE. Insecticides are also part of an IPM program. The PCO should focus on direct applications of insecticides against the adults where they congregate, and a more selective approach against larva and eggs involving use of a variety of insecticides (i.e., pyrethroids, microbials, baits) and formulations (micro-caps, wettable powders, ECs) in combination with cultural control tactics.

For control of adult flies outdoors, a variety of formulations are available. For a more organic/green approach, use boric acid in the bottom of Dumpsters and other trash receptacles. Microbial bacterial products that are new to the industry are good for treating floors of livestock barns, pens and stables before new bedding is placed. Boric acid products and synthetic pyrethroids are both good for treatment of vertical walls and other breeding sites that are not in confined areas or segregated from structural households. Among liquid insecticides, microencapsulated and wettable powder formulations usually work best on rough surfaces exhibiting multiple cracks and crevices. Use fly baits near adult feeding sources. Current imidacloprid baits seem to work well here.

For larvae and eggs, use the methods listed previously in conjunction with removal of bedding or breeding materials to ensure proper treatment of substrate before new bedding is placed. For example, stable flies breed in vegetation material and manure, often including animal waste mixed with soil, straw, hay and other bedding material. The most practical and economical method for reducing stable fly populations is the elimination and management of breeding substrates, regardless of the particular insecticide used. Use of synthetic pyrethroids, as spot treatments where stable flies congregate on rafters and vertical walls, will help reduce adult populations.

Remember, effective fly control cannot be achieved with insecticides alone. Proper animal waste and trash management and good feedlot sanitation must be included in a fly control program. Repeat “IPM, IPM, IPM.” The cleaner your customers’ surroundings are the fewer chances there are for flies to breed. Happy cleaning!

The author is director of research and development, Waterbury Companies, Waterbury, Conn.