Cycle Little house flies (Fannia canicularis) are generally most numerous during the cooler spring and fall months. As temperatures rise in summer, populations of Fannia diminish. Adults are approximately two-thirds the size of the house fly and lack the house fly's distinctive thoracic stripes. Fannia at rest hold their wings over the back more than the house fly does, creating a narrower V-shape to the wing outline. Flying clusters of male Fannia typically form in areas with still air such as breezeways and porch areas of residential homes, maintaining a position 5 or 6 feet above the ground. Strong air currents tend to disperse these male aggregations. Larval Fannia are adapted to tolerate a wide moisture range at their developmental sites, making them a particularly difficult nuisance fly to control. Egg laying and larval development frequently occur in animal wastes (especially chicken manure), but various moist organic materials can serve as suitable substrates. Poultry manure in inland areas of southern California can have abundant coastal fly, F. femoralis. This fly looks much like F. canicularis, especially in the immature stages, but is not a pest affecting humans. Unlike house fly larvae, Larvae of Fannia are brown in color, more flat than round, and have numerous fleshy spines. The developmental time from egg to adult is somewhat longer for little house fly than for the house fly at all temperatures.
Little house flies are more reluctant to enter homes than are house flies; instead, they tend to congregate in outdoor areas such as patios, entryways, and garages. As temperatures decline, they seek cover in buildings or protective vegetation. They seldom land on human foods and are not considered a significant carrier of human disease agents. However, their habit of hovering at face height makes them annoying, though they move readily out of the way when approached.
As with all nuisance flies, eliminating breeding sites is the preferred method of controlling Fannia. Accumulations of manure (especially poultry) or other decaying organic matter are ideal developmental sites. These developmental sites must be removed or spread thin to fully dry. Fannia are not attracted to the same fly baits or traps that collect house flies. Some relief can be obtained by placing fans in areas where male Fannia tend to swarm, as the increased air movement will make the site less attractive to them.
Face flies (Musca autumnalis) are a problem particularly in rural areas of northern and coastal California where livestock are present. The hotter, drier weather in southern California and the southern San Joaquin Valley is not conducive to their development. Face flies require fresh cattle or horse manure for development. The face fly looks virtually identical to the house fly but is somewhat larger and darker in color and male face flies have a distinctive orange-yellow-colored abdomen. Like the house fly, it also has sponging mouthparts and cannot bite. However, face fly behavior is distinctive because they are specifically attracted to the eyes, nose, and mouth of cattle and horses.
Face flies feed on the secretions of cattle and horses in the summer months. Their habit of feeding around the eyes makes them capable of transmitting pinkeye to livestock, and they are a much more successful pinkeye vector than the closely related house fly. In fall, swarms of face flies may enter buildings or similar structures to hibernate through the winter months. On warm days, these hibernating flies can become active resulting in nuisance to homeowners. When active, face flies are attracted to light, so they are frequently found flying inside homes near windows.
To control adult face flies within the home, locate the area where the flies are hibernating and then treat them directly. Begin searching for resting sites on the southern and western sides of the building because in fall and winter these walls receive the most sun and therefore are usually the warmest parts of the building. The flies are attracted to these warm areas when searching for protective wintertime harborage. Face flies seeking shelter will often enter cracks and crevices that lead to structural voids in a building, such as crawl spaces, attics, or false ceilings. These structural voids may need to be inspected if the presence of adult face flies persists throughout the winter.
Flies can be vacuumed off the surfaces on which they are hibernating; in areas inaccessible to vacuuming, a residual insecticide such as a pyrethroid can be applied. For application of residual insecticides, contact a reputable pest control company. To prevent future infestations, cracks on the outside of the building structure that may serve as entry points for flies should be sealed.
For most fly species, the best control is achieved by removing larval developmental sites. Because face flies develop in fresh, undisturbed cattle manure (intact manure pats), removal of larval developmental sites (i.e., removal of intact manure pats) may be very difficult and probably impractical in most circumstances. However, by increasing the density of cattle (generally accomplished by restricting their pasture area), the manure pats will be disturbed, allowing few flies to develop. Also, removal of cattle from nearby fields or pastures may help to reduce the problem.
Garbage flies are a group of fly species with similar life histories and behaviors. Adult flies in this group can be readily differentiated from other flies discussed in this publication by their coloration, which is a shiny, metallic green or blue often mixed with some copper color.
Under ideal temperatures, garbage flies can develop from egg to adult in as little as 7 days. Eggs are usually laid in decaying meats (carrion), garbage, or dog feces. Similar to other nuisance flies, garbage fly larvae leave their developmental site to seek out drier and more protected areas for pupation. This behavior is responsible for the mass emergence of maggots from trash cans that have been sitting with garbage for too long. Garbage fly larvae and house fly larvae look and behave similarly, making identification difficult for the untrained.
Like house flies, garbage flies have sponging mouthparts and do not bite or feed on blood. They are, however, strongly attracted to human foods and garbage and can make cooking outdoors difficult due to the nuisance they pose. As with house flies, they may be involved in the transmission of disease agents picked up from garbage or animal feces and subsequently carried to human foods.
As with the other nuisance fly species, eradication of larval developmental sites is the most efficient means of control. Household garbage and pet feces should be placed in plastic garbage bags and sealed with ties. Garbage bags should be removed from the home at least weekly and placed in a covered garbage can for pickup by a refuse collection service. Garbage cans should be set out for pickup at least once each week even if they are not full because garbage that sits for more than one week allows for the development of adult garbage flies. Finally, garbage cans should be regularly washed out with soap and water to remove any garbage residues that might attract garbage flies or allow for their development.
Vertically hanging, sticky fly ribbons used to reduce adult house fly numbers will not work to control adult garbage flies; unlike house flies, garbage flies do not rest on vertical surfaces. Adult garbage flies can be controlled using inverted cone traps, as for house flies, but traps should be placed at some distance from the home or structure due to their foul odor.
Selective use of insecticides may be considered when sanitation measures fail. Fly baits used for control of house flies are not likely to provide good control of garbage flies because the attractants present in fly baits were designed to attract house flies rather than garbage flies, and therefore may not be very attractive to them. However, when placed on the ground or in containers where garbage has accumulated, some control may be obtained.