Dorothy is a Master Gardener, former newspaper reporter, and the author of several books. Michael is a landscape/nature photographer in NM.
Whirligig Beetles Skimming Across Water
Skilled Swimmers Adapted to Life in the Water
You can find whirligig beetles on ponds, streams, canals, ditches, lakes and slow-flowing rivers, pretty much any body of water you can think of. Habitats with turbulent water or dense vegetation are generally avoided by them. Although there are well over 700 species of them worldwide, as beetles go, they are pretty unique. One of the things that set them apart from other beetles is their short, clubbed antennae. But the eyes of a whirligig beetle are the feature that makes them the most unique.
They have two eyes (one on top of the other) on the left and two eyes on the right (positioned in the same way). One of the eyes on each side allows them to see underwater and one allows them to see above water.
The name of this family of beetles, Gyrinidae, is derived from the Latin word for circle. They have become very well adapted to life in the water and their paddle-like legs have allowed them to become skilled swimmers. Just like other beetles, whirligigs have membranous hindwings covered by forewings modified into very thick and heavy shields, although when their wings are closed, the shield-like forewings will form a straight line right down the back of the beetle.
The name "whirligig" comes from their habit of swimming wildly in circles whenever they are disturbed or threatened. They can be found throughout central Europe and Britain where their presence is commonplace, although there are over 50 species in the United States and Canada.
New Species Identified in the United States
In 2015, a new species was identified by Grey Gustafson, at that time a Ph.D. student at the University of New Mexico. Gustafson found the new species, the first since 1991, in Alabama's Conecuh National Forest while he was hunting for similar whirligig beetles. He was quick to notice that they looked similar to some of the specimens that had not yet been identified at the Enns Entomology Museum.
Gustafson named the new species Dineutus shorti after University of Kansas coleopterist Dr. Andrew E. Z. Short, whom he credited much of his inspiration.
Capable Flyers Who Prefer the Water
Whirligig beetles, which are a metallic black color with orange legs, have wings like most other beetles and they are quite capable at flying. Most of the time when they are flying, they are just searching for water because they simply prefer an aquatic life. Their outer layer is appropriately lubricated and their hind legs are modified and paddle-like, which aids them in swimming.
Adult whirligigs are able to carry an air bubble with them at the tip of their abdomen allowing them to breathe underwater and stay there for long periods of time. When they surface for air, the air bubble is replaced with a new one.
These particular beetles are active during the day and are very social creatures, often found in large numbers swimming around on the surface of the water until they are disturbed, at which time they begin their erratic behavior and often dive to safety.
During Autumn nights, the adults fly in search of water. In July and August, the larvae go through pupation on land. They are protected by a cocoon of plant matter and sand grains and the adult beetles appear 10 days later. Both the adults and the larvae are predatory, preying upon mosquito larvae and other aquatic invertebrates.
Whirligigs as Predators
Whirligig beetles and their larvae are carnivorous. While the adults feed on insects that happen to fall into the water, the larvae will eat other aquatic insects and invertebrates.
Adults are attracted to waves caused by a struggling insect, often crowding around it with each beetle grabbing a bite. Waves are transferred to the antennae, and stationary whirligig beetles can locate drowning insects (or other prey) via the antennae that can sense waves. They are also able to detect prey using echolocation and even the waves produced by their own swimming motion. Plus, they are scavengers, often seen eating dead creatures as well as those that are helpless.
And as Prey
Whirligig beetles have a type of "chemical defense system" giving off an odor that smells a little bit like sour apples. Some of their vertebrate predators don't like the odor, which often protects them from an attack. Their dual vision, chemical defense, and extremely fast swimming movements all help them to avoid predators both above and below the water.
Larvae of the Whirligig Beetle
Larvae of the whirligig beetles are pale, elongated, flattened, having three pairs of crawling legs and eight pairs of featherlike gills which protrude from the sides of the abdomen.
Eggs are laid on the surfaces of submerged water plants. The larvae are not seen as often as the adults, as they spend most of their time on the bottom surface of the water. When they are grown, they crawl out of the water to form pupas on plants that are close by. The adults will return to the water and overwinter in mud and debris, emerging in spring from hibernation to form hunting groups.
Classification of Whirligig Beetles
- Kingdom Animalia
- Phylum: Arthropoda
- Subphylum: Hexapoda (Hexapods)
- Class: Insecta
- Order: Coleoptera
- Suborder: Adephaga (Ground and Water Beetles)
- Family: Gyrinidae
- Genus: Gyrinus
- http://www.arkive.org/whirligig-beetle/gyrinus-substriatus/ (Retrieved from website 7/08/2018)
- https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/whirligig-beetle (Retrieved from website 7/09/2018)
- https://nature.mdc.mo.gov/discover-nature/field-guide/whirligig-beetles (Retrieved from website 7/09/2018)
© 2018 Mike and Dorothy McKenney
Mike and Dorothy McKenney (author) from United States on July 09, 2018:
Me too! I didn't know what they were called back then, but they were fun to watch.
Alexander James Guckenberger from Maryland, United States of America on July 09, 2018:
I remember playing with these things in the stream as a kid. :)