Quote Originally Posted by Mr. TBAGU 420
But how could the bug be "stunned" by the plants THC, when THC isn't even active to get you high until it's heated up.
Human digestive systems don't have the proper chemicals in our stomach to convert D-9-THC to D-7-THC, but some animals DO have the chemicals in their bodies to break it down.

I'm not entirely sure by what mechanism it repels insects, although I don't believe it repels insects (cannabis uses wind and insects for pollination) but maybe deters animals from eating the flowers/leaves/etc. for some reason. Not sure of the mechanism, though...