Question i have a bell hornets nest under my porch, which is an enclosed area. they are coming and going through a crack. i can not see or get to the nest. how do i kill them?
This can be very difficult since you don't have access to the nest, to treat it directly, and these wasps are not attracted to the yellowjacket baits (see http://www.livingwithbugs.com/yellowjacket_bait.html) that are effective for other species. You could try treating the hole through which they are entering/exiting with Termidor Insecticide (see http://www.livingwithbugs.com/termidor.html) as this material is very effective against wasps and ants in general. Be sure to thoroughly treat the sides of the crack so that wasps contact the insecticide as they enter/exit. Otherwise you may need to just cordon off the area around the crack with yellow tape until the nest is less active this winter.
I can answer questions about the control of pest insects, spiders, mites and related arthropods. These household pests include termites, carpenter ants, powderpost beetles, nuisance ants, bed bugs, cockroaches, fleas, wasps, and many others. I can also answer questions about using pesticides and other pest control tools such as baits and traps.
I am a retired university extension entomologist. I've taught and conducted research in urban and agricultural entomology. I've published over 70 extension publications, 20 research publications and several books about insects.