They are very bad around here especially if living in a rural area they simply come in from the fields and the woods after filling themselves on whatever green plants they thrive on. They invade homes into every crack and crevice and hide out the winter. Obviously they do not need to eat during the late fall and winter months. So they wait until the spring to emerge again. Two years ago prior to the use of the moth balls we took the trailer out and turn on the AC and heard this popcorn sound inside the duct works and it was coming from the bugs being blown around inside the duct work. We then noted they had invaded the pump area, water heater area by the tank, storage areas and simply everywhere. Last year I put the moth balls in all these areas and this spring these areas were free of the bugs. When I open the door in the winter I smell the moth balls but that's ok, no bugs. Just be careful and remember everywhere you place them because a high concentration of these moth balls are toxic to humans. I tried everything else including that product home defense but it is not possible to spray that stuff all over everything and beside you need something that is continuously protecting the RV from these bugs and that is the moth ball. I think the moth ball very slowly melts or disintegrates by giving off the chemical aroma over a long time. You see this by their reduction in size. And of course after removal from the RV fresh air will simply remove the odor of the moth balls. I like to ventilate the RV by opening the vent cover on the roof. Before the screen on the vent was covered with these bugs. Now I place a container of moth balls underneath and let the aroma generated by the moth balls drive them away from the vents. Bottom line it works. A friend of mine tried this and told me and thankfully I was about to give up because these bugs are so annoying.