And they are.

"If they were really fascists, it would be illegal to criticize them."

Since my last two Wet Beast Wednesday posts were about animals that live in the Mississippi River (among other places), I've decided that this is going to be my unofficial Mississippi River month. It wasn't planned, but that's how it ended up working out. Anyway, this week's topic is beetles, famously known as God's favorites. I don't often have personal experience with the animals I cover in this series, but this time I can tell you that picking a few dozen of these out of a fyke net while they're all trying to run away from you is not very fun.

(Image: two whirligig beetles floating at the top of the water next to each other but facing opposite directions. They are black beetles with an oval shape and smooth bodies. The limbs are not visible and the antennae are short. End ID)

Whirligig beetles are members of the family Gyrinidae and there are around 700 to 900 species of them. Most species are primarily aquatic, but there are some land-dwellers. The majority of whirligig beetles look pretty similar to each other, differing mainly in size, which can be between 3 and 18 mm (0.1 to 0.7 in). They have black to grey or bronze elytras (the hardened wings that protect a beetle's regular wings and fold over the back when not in use) that are dimpled with tiny pits like the surface of a golf ball. The body is flattened by beetle standards and has an ellipsoid shape that makes them more hydrodynamic. The body is coated with a waxy secretion that provides buoyancy and waterproofing. This substance is constantly being replaced as it wears away. The wax layer is also slippery, making it harder for predators to grab onto the beetles. The hind two pairs of legs are flattened and broad. They act like paddles, propelling the beetle through the water, but making them slower and more clumsy on land. The front legs are long and adapted for grabbing prey. The antennae are unusually short and club-like, which is rare in beetles. The antennae rest on the water's surface, where they can sense the motion of the water. The eyes are divided into two areas each at the level where the beetle will naturally float in the water Above the water level, the compound eyes are adapted to see well in air, while below the water line, they are adapted to see in water. This is a similar adaptation to the four-eyed fish, which also have eyes divided in this manner.

(image: a whirligig beetle from the side, showing off what is normallu under the water. At this magnification, the rows of tiny dimples on the elytra are visible. The back two limbs are short, flattened, and bristly. The front legs are longer. It appears to have two eyes on the side of its head, one pointing up and one pointing down. End ID)

Whirligig beetles are found in slow-moving or still freshwater environments in most of the world, except for Antarctica, Aotearoa/New Zealand, southern South America, and the eastern parts of Polynesia. They spend the majority of their time swimming at the water's surface, looking for prey. The name whirligig comes from the bizarre, twirling motion they make as they swim, referencing spinning children's toys. Whirligigs are the fastest swimming of all aquatic insects. Whirligig beetles are usually found in groups called rafts, swarms, or schools that can be thousands strong. The placement of an individual in the group appears to be a complex behavioral dance based on size, sex, and food availability. Larger individuals and males are usually found near the edges of the raft. In addition, the more recently an individual has fed the more likely it is to move toward the center of the swarm. Beetles on the edges of the swarm have a better chance of finding food but are more exposed to predators. Whirligig beetles are predators who feed on other invertebrates, often insects that fell into the water. They also scavenge on carrion. They prefer to get food at the surface, but are full capable of diving, usually doing so to avoid predators. While diving, they trap a bubble of air under the elytra to breathe while submerged. When threatened, whirligig beetles can release a noxious odor to deter predators. Predators of whirligig beetles include fish and birds. Many species are capable of flight, some up to 20 km in one go, which they use to escape predators and disperse to new habitats.

(GIF: two whirligig beetles swimming on greenish water, showing the spiraling motions they use. End ID)

Whirligig beetles are believed to be semelparous, meaning they mate once and then die. The only source I could find that went in depth about reproduction discussed beetles living in temperate areas as having two mating seasons and generations per year. Mating first occurs in spring as the water warms. The actual mating behavior isn't described, but the eggs are laid in rows on submerged plants. The adults die soon after mating. Gestation takes between 5 and 7 days, with water temperature and species altering the gestation period. Whirligig beetle larvae look almost nothing like the adults. They are long, slender, segmented bugs with 19 pairs of gills emerging from the abdomen. These gills can also be used as fins when the larvae gyrates its body, but they mostly stick to the bottom. Whirligig beetle larvae are predators of other aquatic invertebrates, like snails, slugs, worms, and other aquatic insect larvae. Their mandibles are hollow and used to pierce the prey and inject it with digestive juices, then slurp up the liquefied remains. Once the larval stage ends, the larvae will climb onto shore or an exposed plant and form a cocoon of mud and debris. Inside the cocoon, they pupate and emerge as an adult after 6 to 10 days. The adults will be sexually mature in time to mate again in late summer. This generation will become adults before winter, but will not mate until spring. They spend the winter in a hibernation-like state clinging to the bottom or to plants. In warmer regions, they may remain active through the winter instead.

(image: a whirligig beetle larva. It is a long, slender, segmented bug looking closer to a centipede than a beetle. Feather appendages extend from the side and the head is tipped, with curved, pointy mandibles. It is a pale orange color, getting darker at the head. End ID)

Most species of Whirligig beetle are classified as least concern or data deficient. Most species have not been assessed, though some species are noted to have reduced in population, seemingly as a result of increased fish stocking in their habitats. There is no commercial use for the beetles. There is some interest in studying their movement patterns for use in nanotechnology to figure out ways for nanobots to move in groups without crashing into each other.