The Gray Blister Beetle Epicauta heterodera visiting flowers of Palafoxia for nectar and pollen.  Photo Credit: Archbold Biological Station

Author: Mark Deyrup

The living world may be richer and more interesting than we imagine, so much so that it is a major challenge to formally assess this wealth. At the Archbold Biological Station scientists have recently measured one dimension of this rich living heritage. After much patient work in the field and laboratory, Archbold staff and visiting researchers have recorded and collected specimens over decades allowing compilation of a mammoth list of 1,709 different species of beetles that that have been documented on the Station. There is probably no other site in North America with such a comprehensive specimen-based catalog of beetles.

Why should anybody, aside from a few beetle fanciers be excited about such a multitude of different kinds of beetles? “Residents of Highlands County should be proud of this wealth of beetle species,” says Archbold entomologist Mark Deyrup, who with his wife Nancy compiled the beetle list. “This extreme biological diversity strongly suggests that local natural areas are surprisingly healthy and well-balanced.” A complex and diverse insect fauna is believed to be important to the functioning of many natural systems, just a complex and diverse bacterial fauna in our digestive system is important to human health.

While many local beetles have not been studied, a good number, like those mentioned below, have been the study of research at the Archbold Biological Station and elsewhere.

The Gray Blister Beetle is commonly seen visiting flowers for nectar and pollen. At the Archbold Biological Station it visits at least four species of flowers, probably assisting in pollination of these plants. This beetle is protected by highly poisonous blood that can cause blisters on human skin. Thomas Eisner, who worked for many years at the Archbold Biological Station, showed that if one of these beetles is mishandled it produces a drop of toxic blood from each of its six knee joints. The larva of the blister beetle has a completely different role, attacking eggs of grasshoppers hidden in the sand.

The Scrub Passalus Beetle is a shining brown beetle that may be seen marching along the sand roads at the Archbold Biological Station. This large beetle was unknown to science until 1994, when it was described by Jack Schuster, who discovered the new species among specimens from the Station. This beetle feeds on buried rotten wood, which it digests with specialized forms of gut fungi. Passalus Beetles are known for their complex family life: the adults carefully tend their larvae, and both adults and larvae communicate with squeaking noises. According to Jack Schuster, who studied a related species of Passalus (also found at the Station), adult Passsalus Beetles may have a repertoire of 14 different squeaks, equaling or exceeding the number of vocal signals found in most birds.

The Scrub Passalus Beetle Odontotaenius floridanus is found only on the Lake Wales Ridge and Ocala National Forest in Florida. Photo by Nancy Deyrup.

The diet of the Gopher Tortoise is 100% roughage, resulting in an impressive production of feces, much of which ends up in a privy in the tortoise burrow. The Gopher Tortoise Scarab is a specialized beetle that breaks down tortoise dung. This beetle has olfactory (smelling) plates on its antennae to allow it to detect tortoise burrows as it flies about. Before burrowing into the tortoise dung the scarab folds the sensitive plates into a ball and draws its antennae into slots on the body, thus keeping the antennae clean as the scarab beetle digs into its messy meal. A related scarab beetle can be found on bobcat scats on the Station, and a third species of scarab beetle burrows into decaying mushrooms. There are 44 different species of scavenging scarabs on the Station, each probably represented by thousands of individuals. It’s an army of six-legged recyclers.

Dr. Hilary Swain, Archbold’s Director noted, “Everyone stands in awe of Mark Deyrup’s monumental scientific achievement, cataloging Archbold’s arthropod diversity. We also appreciate the contributions of many visiting entomologists from around the world to this work.  The 1,709 beetles reported for the Station represent nearly 30% of the complete list of arthropod species at the Archbold Biological Station that was recently compiled under a National Science Foundation award—curious readers can search all the species in the Archbold arthropod collection online at https://scan-bugs.org or http://www.gbif.org.

“The sight of a beetle hurrying across the sand should be a reminder of the busy intricacy of a natural community that is home to at least 1,709 beetle species,” remarks Deyrup.  The Archbold entomologist freely admits that the biological roles of many of these beetles are unknown, “But we can be confident that all these beetles are hard at work making a living, not sitting around scrolling through Facebook. Each beetle has its little place in the living world.”