These large assassin bugs are attracted by the black lights set out to attract moths. I think they know there is good hunting with all the insects that come along, as can be seen here. If you've ever seen the nymph of these guys, you'll know why they are called "masked" hunters. The nymphs mask themselves with debris, often lint, dust, or anything else that will make them blend in with their surroundings: https://pbase.com/laroseforest/image/144168593