|Urban Knowledge Master|
Musca sorbens (Weidemann)
|Dog dung fly|
Julian R. Yates III
Extension Urban Entomologist
College of Tropical Agriculture and Human Resources
University of Hawaii at Manoa
The larval stage develops in dog, cat, cattle, horse, goat, and pig dung.
The are found in the Pacific islands such as Guam, Kwajalein, Ebeye, Aitutaki, Samoa, the Solomon Islands, and the Hawaiian Islands.
This pest has become a serious nuisance in rural and urban areas. It lands on people, dogs, and other animals and is not easily scared away.
The following life-history information is based on laboratory studies (controlled conditions) of this pest. Developmental rates will differ slightly from those flies developing under field conditions.
Females deposit their eggs in cracks and crevices of the dung in clusters of several to over a hundred. Females are capable of multiple egg-laying; under laboratory conditions they completed three ovarian cycles within a two-week period. An average of 42 eggs per female were deposited during each cycle. The number of eggs produced by a female can be influenced by female size, longevity, and food quality. Larger clusters were due to multiple egg laying by several female adults. These eggs hatched in about 10 days.
First instar (growth stage) larvae burrowed into the dung and remained there until mature. There are three larval instars which complete development in 4-5 days. Mature larvae left the dung (most often at night) and pupated (immobile growth stage) within a day. In about 5 days adults began to emerge during the late afternoon or early evening, peaked during the morning, and ceased by noon.
In the laboratory, mature larvae left the dung, usually at night, and pupated within a day. In about five days, adults began to emerge during the late afternoon or early evening, peaked during the morning, and ceased by noon.
A higher proportion of females emerged during the first night while a greater number of males emerged during the second night suggesting a differential rate of development of sexes during the pupal stage. The sex ratio (females:males), however, was determined to be 1:1. Within 4-7 days mating occurs and fertilized female adults oviposit (lay eggs) in one to two days thence. Adults of this pest can live for about two months with adequate food and moisture; in the absence of food and water adults did not survive for more than 45 hours.
Adult flight begins at sunrise and ends a few minutes before sunset, suggesting a diurnal (day-night) behavioral pattern. During this period, females are more active than males and are an extreme nuisance to people working in their yards. At night, adult flies can be found on blades of grass, grass flower spikes, and shrubs; they rarely can be found at ground level.
A dispersal study conducted in the field at two locations of Oahu suggests that adult flies can move quickly and randomly out of a breeding site. This behavioral pattern makes control difficult because a single breeding site can affect an entire community. The entire community's effort is necessary for managing the dog dung fly.
An individual's effort to pick up after a pet and dispose of dung in an acceptable manner (bury or seal it in plastic bags) can be fruitless if the procedure is not followed by all pet owners in the community. Stray animals further complicate control efforts.
Nine insecticides have been tested in the laboratory for their effectiveness against female and male adults. The most toxic of those tested were pyrethrins with piperonyl butoxide; dichlorvos; naled; and fenthion. Because the availability and registration of insecticides may change frequently, you should consult your local pesticide supplier (garden shops, for example) for recommended products. It is not a good idea to rely on insecticides as the only way of controlling this pest, however. An attempt to control the house fly in Hawaii through chemical means has resulted in the genetic selection of insecticide-resistant flies.
Ikeda, J. K., R. L. Mau, W. C. Mitchell, and M. Tamashiro. 1979. Toxicity of Insecticides to Musca sorbens in Hawaii. J. Econ. Ento. 72(1):33-35.
Mau, R. L., and M. Tamashiro. 1981. Bionomics of the Dog Dung Fly, Musca sorbens Wiedemann, in Hawaii. Proceedings, Hawaiian Ento. Soc. 23(3):375-386.
Mau, R. L. 1978. Larval Development of Musca sorbens in Animal Dung in Hawaii. Annals Ento. Soc. America. 71(4):635-636.