i found 2 years ago when i finally stripped my sheds down after 3 years of been over run with them, most mites were under the felt on the roof and was absolutely covered sprayed the whole shed inside and out with duramitex twice replaced the felt and have never had a prob since,tried fitcam and many others but it took the duramitex to get rid totally now spray early may inside and out and september and like i say never seen them the last 2 years