I've only had one single crevice rocket used by bats. I did have a problem with paper wasps in it. But I think it may have been due to the crevice size being closer to an inch rather than 3/4". I have observed the least trouble with wasps in houses with narrow crevices.
Interestingly, this house is the only pole mounted house ever used by my big brown maternity colony. Maybe they preferred the wider crevices?
I have only had one paper wasp nest in my lone rocket house. The nest was in the larger chamber which approached 7/8". On the other side the big brown preferred the 7/8" chamber over the 3/4" in which I attracted little browns to.
