An online resource based on the award-winning nature guide

Beetles

Weevil Watching

If you take a close look at the Black-eyed Susan blossoms that can be found in unmowed fields and roadsides this time of year, chances are good that you will find a tiny beetle called a weevil.  A weevil’s mouthparts are formed into a long snout, with one antenna on either side of it. The snout is used not only for feeding but also for making cavities in buds, fruits, seeds, stems, and roots of plants, where eggs are laid. When the weevil larvae emerge, they feed within the plant.

There are 60,000 species of weevils, all of which are herbivorous and most of which are less than ¼ ” long. Most of those found on Black-eyed Susans appear to be feasting on pollen. Many weevils are pests of plants such as cotton, alfalfa and wheat. You may have even found them inside your house devouring your cereal or flour.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Predaceous Diving Beetles Seeking Prey

There is a family of water beetles, Dytiscidae, known as Predaceous Diving Beetles.  As their name implies, these beetles are predatory.  They don’t hesitate to attack prey larger than themselves, delivering a sharp bite with their jaws to small fish, tadpoles and frogs.  They then immediately inject enzymes that digest the prey so that the juices can be ingested.

Predaceous Diving Beetle larvae, called “water tigers,” are also predators, grabbing prey with their pincer-like jaws. The larvae are elongated, flattened and can be 2 inches long. They hunt by holding still, waiting with jaws wide open, and then strike suddenly, clutching the prey tightly with their jaws. As with the adults, the pincers are hollow, enabling them to begin sucking the juices of their prey while grasping it. They are often seen when they come to the surface of the water to draw air into spiracles located at the hind end of the body.

Adult Predaceous Diving Beetles are collected by young girls in East Africa. It is believed that inducing the beetles to bite their nipples will stimulate breast growth. Having recently had my toe bitten by a Predaceous Diving Beetle, I can testify that this is not a practice that most females (or males) would enjoy. (Photo: Predaceous Diving Beetle with remains of prey)

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.

 


Fire-colored Beetle Larvae

11-19-18 fire-colored beetle _U1A1193 (1)

Peek under the loose bark of rotting logs, both deciduous and coniferous, and you’re bound to find the larva of a beetle known as a Fire-colored Beetle (family Pyrochroidae).  Its common name is derived from the Greek word pyros (“fire”) + chroma (“’color”), a reference to the bright color, often red, of the adults of some species.   From one to several years are spent in the larval stage. Adults of the Pyrochroinae emerge from late spring to midsummer and are primarily nocturnal.

Many adult Fire-colored Beetles are attracted to cantharidin, a toxic compound produced by Blister Beetles.  Males locate a Blister Beetle, climb onto it and lick off the cantharidin that Blister Beetles exude and use the blistering agent to impress a female of their own species. When mating takes place, most of the cantharidin is transferred to the female in the form of a sperm packet.  The eggs the female subsequently lays are coated with cantharidin to protect them from being eaten before they hatch. (Bugguide.net)

Naturally Curious is supported by donations. If you choose to contribute, you may go to https://naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Black Blister Beetles Consuming Asters

9-7-18 black blister beetle_U1A8536

Blister beetles are so-called because they contain a chemical in their hemolymph, or blood, called cantharidin.  If rubbed or pressed the beetles release cantharidin as a defense mechanism, which causes blistering on human skin.  The Black Blister Beetle (Epicauta pennsylvanica) belongs to a genus of beetles that are highly toxic to horses — a few beetles fed in a single feeding of alfalfa can be lethal.

As larvae, most blister beetles are predators, often invading wild bee colonies and consuming bee larvae, as well as nectar and pollen.  Black Blister Beetle larvae and other blister beetles in the genus Epicauta prey on the eggs of grasshoppers.  Female Black Blister Beetles lay clusters of eggs in the soil in late summer. The small, active larvae that hatch from these eggs crawl over the soil surface entering cracks in search of grasshopper egg pods which are deposited in the ground. After finding an egg mass, the blister beetle larvae become immobile and spend the rest of their developmental time as legless grubs. The following summer they transform into the pupal stage and soon emerge in the adult stage. This is why blister beetle numbers increase dramatically following high grasshopper populations.

Once they mature into adulthood, Black Blister Beetles feed on plants (phytophagus) and are commonly found on flowers, especially those in the Aster/Composite family. They are said to be there for the nectar and pollen, but the Black Blister Beetle pictured denuded several aster blossoms of all petals during the time it was observed.

Naturally Curious is supported by donations. If you choose to contribute, you may go to https://naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


The Emerald Euphoria Beetle: A Distinctive Scarab

6-20-18 emerald euphoria beetle_U1A8526

Beetles comprise almost 40% of described insects and 25% of all known animal life-forms. There are about 30,000 beetles known as scarabs or scarab beetles in the family Scarabaeidae. They make up about 10% of all known beetles. You may be very familiar with scarab beetles without even being aware that that is what they are – they are as close as the nearest Japanese Beetle or June Bug (beetle).

Scarabs are generally oval-shaped and stout. The smallest are about .08 inches and the largest (Hercules beetles) can reach 6.7 inches. Most scarabs are black or brown, but many, especially tropical species, have bright colors and intricate patterns. They have distinctive, clubbed antennae composed of plates called lamellae that can be compressed into a ball or fanned out like leaves to sense odors (see photo). Their diet is extremely varied and includes plant material, fungi, fruit, carrion, insects and even the slime left by snails.

One fruit- and flower-eating species is the Emerald Euphoria beetle, Euphoria fulgida (pictured). It is usually bright green or bluish. Emerald Euphoria beetles belong to the subfamily Cetoniiae, the flower or fruit chafers. One of its most distinctive characteristics is its ability to fly (using its second pair of wings) while its first pair (the hardened, colorful elytra) remain closed — most beetles open and extend their elytra during flight.

Unlike most scarabs, Emerald Euphorias are diurnal, making it possible to see this species visiting flowers in order to consume nectar, pollen and petals.  (Thanks to Richard Wyatt for photo op.)

Naturally Curious is supported by donations. If you choose to contribute, you may go to https://naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Blister Beetles Mating

5-9-18 blister beetles mating_U1A1519Blister beetles derive their name from the fact that they secrete a yellow blood-like substance called hemolymph which contains the blistering compound cantharidin. Severe burns and even poisoning can occur if the quantity encountered is large enough. (Baled hay containing the carcasses of blister beetles can be lethal to livestock that eat it.)

Defense isn’t cantharidin’s only function, however. Cantharidin is secreted by the male blister beetle and given to the female as a copulatory gift during mating. Afterwards, the female beetle covers her eggs with it as a defense against predators.

Naturally Curious is supported by donations. If you choose to contribute, you may go to https://naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Ladybugs Maturing & Seeking Shelter

9-27-17 ladybug IMG_6065

Ladybugs, along with roughly 88% of all insects, pass through four separate stages (egg, larva, pupa, adult) in their life cycle. This form of maturation is referred to as complete metamorphosis. Like many other insects that experience complete metamorphosis, the larval, pupal and adult stages do not closely resemble one another. While most of us would have no trouble recognizing an adult ladybug, the two middle stages are strikingly different from the adult spotted beetle we’re familiar with. After a ladybug egg hatches, the larva emerges, looking a bit like a tiny alligator. Anywhere from seven to twenty-one days later and after several molts, the larva attaches itself to a leaf and pupates. The pupa assumes yet another bizarre form, which some feel resembles a shrimp. Within a week or two the pupa matures and transforms into an adult ladybug. Most species of ladybugs hibernate (technically enter “diapause,” as it’s referred to with insects) as adults in large groups under leaf litter, logs and other protected spots.