The answer has to be in non chemical solutions wherever that is possible. For many years the use of heat treatment was widespread in the museum world to kill beetles and moth. The process was based on sound biological principles. Lipids in the nerve membranes and waxy layers of the insect cuticle degrade. The polypeptide chains of proteins lose their characteristic structures.
Folded structures become unfolded and turn into random configurations.
To put simply the effects of heating, especially repeatedly, were damaging. Objects were prone to cracking, shrinkage and distortion because of dehydration. This made the treatment unacceptable for sensitive material and the practice has largely died out. So to recap, what we had was a non chemical solution to the pest problem that was highly effective but posed a risk to the subject because of dehydration. It was to take some 50 years for technology to develop to such a stage that it could provide an answer to the dehydration issue.