Powderpost beetles

I have had my house sprayed twice for powder post beetles and months have passed without seen any activity and just today I’ve noticed a couple of Powder hills what can I used to further treat since they don’t seem to be going away? Hamilton. ON

In many instance, retreatments are necessary for control of powderpost beetles, as standard surface applications of pesticides will kill only emerging adults rather than larvae since the insecticide will penetrate only slightly into the wood. In cases of very extensive infestations, particularly in hard-reach areas, fumigation may be required.