I’ve been fascinated with social insects since my early childhood. I have watched ants in their natural habitat and constructed artificial nests to observe them in the fall and winter. This experience was influential in my future career choices. I received a Ph.D. in entomology from the University of Wisconsin in 1989 and will soon be moving to Louisiana State University to be their resident urban entomologist. Dr. DeFoliart asked if I would relate some of my knowledge on collecting ant pupae for the readers of this newsletter.
I’ll deal only with the mound-building ant species in the genus Formica, since this ant group I know best. Formica is known for its spraying of formic acid as a defense mechanism. The large gland reserve appropriated for this purpose makes eating adults a distasteful experience. Even an ant with a full load of sweet honeydew in its crop tastes extremely acidic. The pupae on the other hand, do not have this acid flavor and are, if I must admit it, quite tasty.
Having dug into so many mounds to document the colony cycle of Formica, I learned that the brood cycle is very predictable for a given species in any one region. Regular checking of a single mound will
quickly reveal when the pupae can be harvested from all the mounds. Ant workers take meticulous care of their young. The smallest larvae are kept in moist areas of the mound. The pupae however need dry and warm conditions and are kept separate from the rest of the brood. The mound-builders make it particularly easy for pupae collection because the workers move them to the highest reaches of the mound where the sun can warm them. Formica adults will even remove the paper-like cocoon from the pupae several weeks before they have sclerotized, sort of like shelling peanuts.
The best time to go pupae collecting is one hour after the sun has hit the mound in the morning. The pupae can be collected just under the surface of the mound at this time. Later in the day the pupae will be moved deeper into the mound to avoid excessive heat. After collecting the pupae, replace the soil and thatch to its original place. By collecting in this way the colony itself will be little affected by the harvest and will quickly rebound from the loss. This is particularly important since ants (especially Formica) are one of our most beneficial insects in the world and must be respected as such.