The invention relates to methods and apparatus for attracting and trapping or otherwise disabling insects, and, in particular, to a counterflow device that produces CO.sub.2 gas and then cools the CO.sub.2 gas for use as an insect attractant in an outflow from the trap.
Suction traps have been used in a variety of configurations to trap or kill insects. It is known to use screened material to trap the insects thus drawn into the trap, and to use mechanical, electrical or poison means to disable, injure or kill the insects. It is also known to use fan mechanisms to generate the suction flow, and to use lights or air-borne attractants, such as CO.sub.2 and 1-octen-3-ol (octenol), to lure the insects to the vicinity of the trap. In some configurations, such as disclosed in U.S. Pat. No. 3,196,577 (Plunkett) and U.S. Pat. No. 5,157,090 (Cody), a small flow of an insect attractant is exhausted from the device to the outside of a much larger suction stream.
CO.sub.2 gas used as an attractant is typically provided from a pressurized canister or by the sublimation of dry ice. The CO.sub.2 gas thus produced is at ambient temperature or lower, and is released in a substantially undiluted state to the vicinity of the trap.