G. C. LaBrecque

Mating Competitiveness of Chemosterilized and Normal Male House Flies.

Male house flies sterilized by feeding on a diet containing 1 percent of apholate (2,2,4,4,6,6-hexa(1-aziridinyl)-2,4,6-triphospha-1,3,5-triazine) were as successful as normal males in competition for mates. The percentage of sterile eggs laid by females in cages containing normal and chemosterilized males was as high as, or higher than, would be expected from the ratio of sterile males present.

Dynamics of House Fly and Stable Fly Populations

The relative densities of populations of the house fly, Musca domestica L., and the stable fly, Stomoxys calcitrans L., were studied in north central Florida for 1 year to investigate fluctuations in density and rates of population growth. The density of both species changed gradually, increasing during the spring, stabilizing during summer and early fall, and decreasing from fall until the following spring. When these insects were subjected only to normal environmental stress (no attempt made at control), they had rates of increase from generation to generation of less than 1 to 6X, and the rates were usually less than 3X.

Effect of Gamma Rays and/or Fluorescent Pigments on Sterility and Survival of the Stable Fly

Comparative studies on the relative effectiveness of two ^6^0Co irradiators differing only in dose rate showed that both were equally effective in producing sterility in the stable fly Stomoxys calcitrans (L.). Survival was superior, however, in those flies irradiated with the higher dose rate unit. Marking with fluorescent pigments produced an increase in daily mortalities regardless of whether or not the flies had been irradiated.

Resistance of house flies (Diptera: Muscidae) to dimethoate and ronnel in Florida.

A statewide survey was made to determine the resistance to dimethoate and ronnel of house flies, Musca domestica L., collected from poultry or dairy farms at 32 locations throughout the state of Florida. Compared to flies from the susceptible Orlando strain, flies from dairies were 4.9 to 21.2-fold more resistant to ronnel, and flies from poultry farms were 3.8 to 54.5-fold more resistant. Also, fly strains from dairies were 3.4 to 31.0-fold more resistant to dimethoate than flies from the Orlando strain, and fly strains from poultry farms were 1.8 to 28.5-fold more resistant.

House fly, Musca domestica, control with chemosterilants and insecticides.

Field tests in poultry-caged-layer operations showed that 0.5% hempa + 0.5% thiourea or 1.0% hempa in sugar bait, 1.0% trichlorfon in granular sugar bait, and 1.0% dimethoate in water applied to the droppings at the rate of 1 g active ingredient/m^2 all gave good control of house flies, Musca domestica L. Releases of sterile flies in a pig-rearing establishment combined with weekly larvicide treatments (1.0% coumaphos in water at the rate of 1 g/m^2) reduced the field fly population by more than 5-fold.

Tests with Larvicides for the Control of House Flies, Musca Domestica (Diptera: Muscidae), in Poultry Houses

Infestations of house flies, Musca domestica L., are a continual problem around poultry establishments where caged laying hens are maintained. The customary undisturbed (for several months) accumulation of droppings beneath the cages provides an excellent breeding medium for house fly larvae. The result is a fly population that tends to intensify during the warm months. The high level of resistance adult house flies have developed toward organochlorine and organophosphorous compounds (Wilson and LeBrecque 1960) has caused a need for more effective materials. Wilson and LaBrecque (1960) met with some success in tests with several compounds as larvicides against natural populations of house flies. The results given in this paper are a continuation of that work. Twenty-one compounds were tested as larvicides against natural populations of house flies breeding in manure under caged poultry in the Gainesville, Florida area. The chemicals were applied as emulsions or as suspensions of wettable powders at the rate of 200 mg active ingredient/ft2. All applications were made with a 3-gallon compression sprayer; 2 gallons of the liquid spray were used for each 800 ft2 of breeding area. Larval density was determined by collecting a large spoonful of manure from each of ten locations where the heaviest infestations were apparent, spreading the samples on a plywood panel, and counting the number of larvae present. The effectiveness of the treatment was determined by comparing the difference in counts made before and on days 1, 2-3, and 7 after application, and, in one instance, on days 9-11, 14, and 21 after application. The formulations used and the results obtained are shown in Table 1.

Residual Sprays for the Control of House Flies, Musca Domestica, in Dairy Barns

Control of the house fly, Musca domestica L., in dairy barns has become an increasingly important problem in recent years because of rigid restrictions on pesticide residues in milk and the ever-increasing list of insecticides to which house flies have developed resistance. The first problem can be somewhat alleviated by using organophosphate and carbamate insecticides that are more biodegradable than the chlorinated hydrocarbons; however, we must apparently live with resistance until new means of control are developed. For the present, the continuing evaluation of new insecticides is necessary. The present paper reports evaluations of 9 insecticides made in field tests during the summer of 1966.

New Insecticides that Show Residual Toxicity to House Flies (Diptera: Muscidae)

Ninety candidate insecticides were compared with ronnel (standard) as residual treatments against susceptible and resistant house flies, Musca domestica L. Ten compounds were 90-100% effective against susceptible flies for the entire 24-week test period.

Residual Toxicity of Some Insecticides to Adult House Flies

Of 75 chemicals tested as residues against insecticide susceptible house flies, only 11 caused 90% or more mortality throughout the 24 week testing period. Of these only Bayer 78389 and CELA K-37 were effective for 16 and 8 weeks respectively against an insecticide resistant strain.

Hercules AC-5727 as a residual spray for adult mosquitoes.

Residues of Hercules AC-5727 ( m -isopropylphenyl methyl carbonate were highly effective against adults of Anopheles quadrimaculatus Say, A. albimanus Wied., Aedes taeniorhynchus Wied., and A. acgypti (L.). In laboratory tests with A. quadric maculates on plywood panels, dosages as low as 1 mg. per square foot produced 100% mortality for at least 20 weeks. The compound was better than DDT, malathion, dieldrin, or Bayer 29493 (Baytex®; O, O -dimethyl 0-[4-(methylthio)- m -tolyl] phosphorothoate). Its outstanding characteristic is the rapidity with which it acts, for a 1-minute exposure to deposits of 100 mg. per Square foot consistently produced 100% knockdown within 5 to 10 minutes throughout the first month. Hercules AC-5727, malathion, and DDT did not have long residual toxicity on white-wash or sun-dried brick. In buildings naturally infested with A. quadrimaculatus , Hercules AC-5727 and DDT were still giving excellent protection after 18 weeks. Both were more durable than malathion.