@LouisIngenthron the people who dont want them flying around your food?
@freemo Both the meaning of the idiom and choice of the word "catch" imply a desire to attract rather than repel.
@LouisIngenthron it may be a euphemis but it is the language you use. "I put out a fly trap to catch flys" i cant imagine anyone thinking this means anything other than an undesirable insect.