CIRCULAR No 247 NCrt 



UNITED STATES DEPARTMENT OF AC rR^WSVlRin 



WASHINGTON. D. C. 



E 4 R 'BK 2 



A BOX-TYPE TRAP TO AID IN THE CONTROL OF EYE 

 GNATS AND BLOWFLIES 



By D. C. Parman, Associate Entomologist, Division of Insects Affecting Man 

 and Animals, Bureau of Entomology 



In the course of investigations of the eye gnat, Eippelates pusio Loew, a 

 veritable scourge of man, in Coachella Valley. Calif., a new trap for capturing 

 these insects was developed. The first traps were constructed entirely of 

 glass set in wooden frames. Traps were later constructed of wood, iron, and 

 screen cloth, or a combination of all these and glass. The latter type of trap 

 has been used three seasons experimentally, and during the last two seasons the 

 same type of trap has been developed in several sizes for catching blowflies. 

 At the present time this type of trap is the principal reliance for control of eye 

 gnats in Coachella Valley, where the eye-gnat population has apparently been 

 decimated during the last two seasons by systematic use of the trap. It is 

 thought that the blowfly trap will be found useful on ranches of the Southwest 

 where blowflies are troublesome. 



MAIN FEATURES OF THE TRAP 



The main features of this type of trap are: (1) Large quantities of baits can 

 be used to disseminate odors without requiring the hovering insects, such as 

 eye gnats, to enter the region where odors are so concentrated as to appear to 

 be more or less repellent; (2) immature insects breeding in the baits are pre- 

 vented from escaping; (3) both chemotropic and phototropic responses of in- 

 sects can be utilized; (4) the trap can be adapted to permit insects to enter it 

 without entering the bait chamber; (5) it can be constructed in sizes large 

 enough to handle large carcasses on ranches where it is not feasible to burn 

 the dead animals and in places where it would be advantageous to use large 

 quantities of garbage for baits until it could otherwise be disposed of; (6) the 

 odors are disseminated by Currents of air which forcibly enter the bait cham- 

 ber through the funnel-shaped openings; (7) it may be possible to utilize the 

 trap in breeding a continuous supply of parasites and predators of the insects 

 to be controlled. 



Several traps of this type, in different sizes, have been constructed and tested 

 under different conditions for both eye gnats and blowflies, as well as house flies. 

 The list of materials and instructions for constructing a blowfly trap (fig. 1, A) 

 42 inches wide, 60' inches long, and 77 inches high, inside measurements, are 

 contained in a mimeographed circular (E-299) which will be sent on applica- 

 tion to the Bureau of Entomology, United States Department of Agriculture, 

 Washington, D. C. This circular also shows modifications of this trap for use 

 against eye gnats. 



ADAPTATION OF BOX-TYPE TRAP FOR TRAPPING EYE GNATS 



The eye-gnat trap (fig. 1, B) is fundamentally the same as the blowfly trap, 

 with modifications that adapt it to the habits and size of eye gnats. The trap 

 illustrated is 48 inches wide, 74 inches long, and 103 inches high. 



The writer's investigations have indicated that stirring the baits, especially 

 liquid baits such as are used for eye gnats, greatly increases the catch. Late 

 in the season of 1930 a windmill bait agitator was developed and tested. While 

 it was obvious that eye-gnat catches were materially increased and there was a 

 marked increase in blowfly catches, no conclusive comparative data were ob- 

 tained. These agitators are quite simple and inexpensive. 



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