Drugstore beetles are also a huge problem for natural history museums because they will eat all kinds of biological materials like dried plants. I am curator of

Drugstore beetles are also a huge problem for natural history museums because they will eat all kinds of biological materials like dried plants. I am curator of a medium sized herbarium and we have been fighting beetles since 1945. PDB (paradichlorobenze; moth balls) used to be a very effective way to keep beetles out of collections, but most institutions no longer allow its use. Freezing specimens is what we do now, and it is very effective in the short term, but it has to be repeated at least every few years and it also causes some wear on the specimens. During COVID lockdowns when some specimens were not frozen regularly, the results were devastating. Pressed flowers reduced to dust, trays of pinned butterflies completely gone, only beetle grass left behind. Once you have these beetles they come back again and again. The only really good long term solution is to store everything in what is essentially a giant walk-in refrigerator. ...or if the specimens are old enough, they may have been treated with mercury or arsenic, which is quite effective but has other problems!