Some Insect Pests are Nature's Helpers
An old saying holds that "What is good for the goose is good for the gander!" I don't know much about the wants and needs of male and female geese. But without prompting a firefight about gender inequities, I suspect that a goose and a gander don't always have the same needs.
In addition, the idea of good and bad is meaningful only in human terms. In nature, everything plays a role. And that role is neither good or bad. So it is with the insects of the world.
Humans, though, have other ideas when it comes to classifying things in nature. We like to look at nature in terms of "What did you do for me lately?" So, insects are either good or bad depending on how they affect what we want.
An insect that feeds on plants, in ecological terms, would be called an herbivore. Herbivore does not connote goodness or badness. It is a non-judgmental name for what the creature does. In this case, eat plants.
We humans claim some plants as our own-plants like crops, lawn grasses, flowers and trees for wood or decoration. When we claim a plant and an herbivore shows up to have a meal, we get bent out of shape. We even have a name for such a creature-pest! We then do what we can to make life miserable for the pest.
Fickle creatures that we are, we sometimes find insects to be both good and bad, for instance, those insects known as dermestid beetles. These insects belong to the family dermestidae and play an important role in nature as recyclers of the skin and hair of dead animals. That is the basis for the name dermestid. It is from the Latin root derm, which means skin.
Dermestids are also called hide beetles or carpet beetles. The latter name suggests the source of the problem with these insects. As nature's cleaner-uppers, they take their job seriously. Material from dead animals, like wool in mittens, socks, suits, or carpets, leather or fur in coats, or animal-skin rugs is a signal for egg laying. When hatched, the larvae begin to feed on the natural material and that is when we end up with holes in our best woolen clothing. Of course, the owner of the clothing doesn't appreciate that the insect is just doing what nature ordained it to do!
Resourceful humans have found a way to use the dermestid beetles. These insects are also called museum beetles. They have that name for good reason. Dermestids are used to clean up bones that are destined for museum displays. No one wants to look at a display skeleton that has bits of dried flesh and skin attached. So museum curators clean up skeletons for display by placing the bones in containers that have a population of some dermestid beetles. The beetles do their work. The bones are nice and clean, and ready for display and viewing by museum visitors.
But in a museum setting, the dermestids pose a severe hazard. After all, many museum exhibits feature stuffed animals that have their natural skin and fur or feathers. So dermestid beetles can destroy the exhibit by feeding.
Dermestid beetle feeding can also damage insects in collections. The dead insects are just as good as skin and hair as a food resource for immature museum beetles. Many a private insect collection has been turned to dust and a few odd wings by the feeding of these beetles. That is why insect collectors frequently treat their insect specimen drawers with insect repellents. The chemicals are used to make sure that the only insects present are dead ones!
It just goes to prove that humans are fickle animals. We can't make up our mind about the dermestid beetles. We want them to get rid of the road kill. We don't want them to get rid of our woolen socks. We want them to eat the skin from museum skeletons. We don't want them to eat the dead insects in museum drawers. At least, dermestid beetles don't worry about split personalities!