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Beetles

Predaceous Diving Beetles Remaining Active

10-9-14   p. diving beetle 143While meadows and fields are experiencing a sharp decline in insect life at this time of year, one habitat where insects remain active in the fall and often through the winter is ponds. Among the year-round active pond invertebrates are Predaceous Diving Beetles, which can still be observed as they row through the water, intermittently surfacing to thrust their abdomen above the water line in order to procure a bubble of air from which they breathe. Their middle and hind legs are fringed with long hairs, making them efficient at rowing through the water in search of prey or detritus to eat.

Predaceous Diving Beetles lay their eggs on and in plants above the waterline in early spring. When the eggs hatch, the larvae drop into the water. Mature larvae crawl out of the water to pupate in damp chambers on the shoreline. They emerge as adults and re-enter the water, where they remain active through the winter, under the ice. (Water Scavenger Beetles look a lot like Predaceous Diving Beetles, but they stroke first with one leg, then another, not simultaneously like Predaceous Diving Beetles, and they come to the surface of water head first to secure air.)

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Tortoise Beetle Larvae Making Fecal Shields

8-1-14  tortoise beetle larva with fecal shield 049Instead of discarding feces, or frass, some insects save their waste matter for defensive purposes such as “fecal shields.” These are coverings over the back of the larvae that are made largely of feces and provide either physical or chemical barriers to predation. Adult Tortoise Beetles have a type of shield (hence, their name), but it is formed from expanded, hardened forewings, and is not a fecal shield. The larvae of these beetles have fecal shields which serve as chemical deterrents, preventing most predators from even touching them. The deterrent in the feces comes from the beetles’ food source — plants in the order Solanales. Tortoise Beetle larvae have what is known as a “fecal fork” on their last abdominal segment, which they hold over their body. The larvae maneuvers its muscular, telescopic anus, or “anal turret” in such a manner as to excrete its feces and bits of shed exoskeleton onto the fecal fork, forming an umbrella-like fecal shield.

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Carrion Beetles Feeding

7-30-14 carrion beetle feeding 129When an organism dies, such as the pictured American Toad, a series of decomposers appear and break it down. Some of the first insects to arrive at the scene are blowflies, and they lose no time in laying eggs which rapidly hatch into larvae, or maggots. A bit later, carrion beetles move in. Both of these insects live in dead carcasses, where they eat raw flesh and fungi. There is great competition, believe it or not, for rotting bodies, and carrion beetles such as the pictured American Carrion Beetle (Necrophila americana) have managed to find a way to eliminate some of it. They carry tiny mites on their backs which travel from carcass to carcass with the beetles, devouring the eggs of maggots as well as the smallest maggots themselves. In addition, carrion beetles secrete a strong offensive odor that irritates other insects and predators, a second effective way to reduce the number of insects competing for a corpse.

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Twelve-spotted Tiger Beetle Larva at Work

7-24-14 tiger beetle adult and larva 040Without doubt, I have one of the most erudite readerships in the land of blogs. Several people recognized this uncommon phenomenon. To clear up a few misconceptions, however, being a male, this dragonfly was not laying eggs. Neither was it fertilizing them – male dragonflies perform this act when coupled with a female. This Chalk-fronted Corporal had the misfortune to sun itself on a tiger beetle-inhabited patch of sand. One of the most aggressive groups of insect predators is the tiger beetle family. They are especially known for their speed – up to 5.6 mph, which is comparable to a human running 480 mph. If you watch an adult tiger beetle hunting, you’ll notice that it stops and starts frequently. This is because it runs so fast it goes blind — its brain has trouble processing the information it sees, and the beetle must stop to regain its sight.

The larvae of the Twelve-spotted Tiger Beetle live in tunnels that they dig in the sand (some of you noticed tiny holes near the dragonfly) that can be up to a foot deep. The larvae have hooks located on the back of their abdomen to anchor them to the side of the burrow. Tiger beetle larvae are also predators, and after digging a tunnel the Twelve-spotted Tiger Beetle will crawl up it until just the top of its head is visible. From this position the larva watches for prey wandering by. When it sees a potential meal, such as yesterday’s dragonfly, it flips backwards faster than you can blink an eye and grabs its prey, pulling it down as far as it can into its tunnel, where it safely feasts on its catch. The portion of the Chalk-fronted Corporal’s abdomen that was inside the tiger beetle tunnel was completely consumed except for the outer skeleton.

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Eyed Click Beetle

7-10-14 eyed click beetle 789Although this Eyed Click Beetle (Alaus oculatus) looks ferocious with its large, black “eyespots” (actual eyes are below antennae), it is harmless to humans. Like all members of the click beetle, or Elateridae, family, it gets its name from the sound it makes when it flips itself upright. Click beetles possess a spine-like structure as well as a notch under their thorax. When they release the spine from the notch, it snaps and they are propelled into the air. Click beetles use this mechanism to right themselves if they are on their backs. Entomologists feel predators are deterred not only by the false eyes, but by this action. The larvae, called wireworms, spend most of their life (2 to 5 years) in the soil feeding on decaying plants and other insects in the soil before emerging as adults. (Thanks to Liz Ambros for photo op.)

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Scarab Beetle Antennae

6-16-14  scarab beetle antennae 261Beetles in the family Scarabaeidae share several characteristics, including specialized antennae. The last three to seven segments of each antenna form flat plates, or lamellae, that can be expanded like a fan (see Japanese Beetle insert) or folded together into a club (see June Beetle photo). When these plates are separated they are being used as sensory devices to detect odors. When folded together, the antennae are used as clubs by some species of fighting male scarabs. The next time you see a June Beetle, Rose Chafer or Japanese Beetle, take a second to inspect its antennae before parting company.

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White-tailed Deer Scavengers

deer carcass2  028According to NPR, each year Americans waste 33 million tons of food (and much of this ends up in landfills where it produces methane, a potent greenhouse gas). This situation is totally alien to that of other animals in the natural world, which seem to find a use for any and every organic particle. Great crested flycatchers incorporate shed snake skins into their nests, beavers build dams and lodges with branches they have eaten the bark off of, ermine line their nests with the fur and feathers of prey — the list goes on and on. When it comes to food, there is equally little waste. The carcasses of animals do not linger long, as almost every atom of their bodies is recycled. Fishers, coyotes, foxes, raccoons, opossums, bald eagles, hawks, woodpeckers, ravens, crows and many other animals make short work of a dead deer in winter. Come spring, if there’s anything left, the final clean-up crew consists of legions of turkey vultures, beetles, flies and bacteria, among others. How unfortunate we’ve strayed so far from a process that’s worked for so many for so long.

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