An online resource based on the award-winning nature guide

Insects

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.

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Snow Flies Appearing

1-29-18 snow fly IMG_9481It always comes as a surprise to see tiny creatures moving nimbly over the surface of the snow. However, there are quite a few insects and spiders that do, thanks to the glycerol that they produce in their body fluids that keep them from freezing. The Snow Fly (Chionea sp.) is a type of wingless crane fly.  Most likely its lack of wings is due to the fact that at sub-freezing temperatures it would be very hard to generate enough energy for maintaining flight muscles. They (along with other flies, mosquitoes and gnats) do have two vestigial wings called halteres, the little knobs on the fly’s thorax. They inform true flies about the rotation of their body during flight, and are thought to act as sensory organs for the flightless Snow Flies.

Throughout most of the year Snow Flies can be found in leaf litter, but come winter the adults emerge, mate and lay up to 200 eggs. The lack of predators such as dragonflies and most insect-eating birds makes winter a relatively safe time for Snow Flies to be out and about. Their life span is about two months, during which time they drink by pressing their proboscis against the snow, but they don’t eat.   (Snow Fly in photograph is a female, measuring less than ½”.)

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Broad-shouldered Water Striders Still Active

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If you see what look like miniature water striders skating on the surface of a stream or pond, you may have come upon an aggregation of Broad-shouldered Water Striders, a different family of water striders from the ones we commonly see. They are tiny (2-6 mm) and very fast-moving, zipping here and there with the speed of a bullet, staying on top of the surface film, or surface tension, that is created by the attraction of water molecules. Adaptations to this mode of travel include non-wettable hairs at the ends of their legs that don’t disrupt the surface tension, and claws that are located a short distance up the outermost section of their legs rather than at the end of their legs, so as not to break this film.

Broad-shouldered Water Striders are often found in the more protected areas of a stream, where they tend to congregate in large numbers. Members of a common genus, Rhagovelia, are known as “riffle bugs” and are often found below rocks that are in the current. Broad-shouldered Water Striders locate their prey (water fleas, mosquito eggs and larvae, etc.) by detecting surface waves with vibration sensors in their legs. There can be up to six generations a summer (photo shows that they are still mating at the end of October). Broad-shouldered Water Striders spend the winter hibernating as adults, gathering in debris at the edge of the water or beneath undercut banks.

 

 


Western Conifer Seed Bugs Seeking Winter Shelter

western conifer seed bug 049A6232Every year I receive questions about this unusual-looking insect which is often found on and in houses in the fall. As a result, I publish a post about it every couple of years.  For those of you with good memories, please excuse the repetition.

Roughly 30 years ago Western Conifer Seed Bugs (Leptoglossus occidentalis) started moving east. They are now well established coast to coast. Here in the East they seek shelter during the winter, often choosing to share our domiciles with us. Fear not – though they look fairly menacing, they will do you no harm. Western Conifer Seed Bugs do not bite or sting, and in their semi-dormant condition they do not feed or breed. If you choose not to co-habit with these bugs, be forewarned. When disturbed, they can emit a noxious smell.

In the spring they will vacate your house and feed on the sap of the young cones and flowers of conifers, including Eastern White Pine, Red Pine, Scotch Pine, White Spruce and Eastern Hemlock. Mating takes place, eggs are laid and the young nymphs feed on conifer seeds which they find by detecting the infrared radiation that the cones emit.

These bugs are also called “leaf-footed bugs,” and if you look at their hind legs you will see that a section, the tibia, is flattened. Some species display this specialized leg structure during courtship, and others may use it for defense purposes.


Grasshopper Eggs Incubating

Grasshopper egg pods.

Most grasshoppers mate in the fall, lay eggs and die. Their eggs are deposited in the soil, in a cluster held together by a frothy secretion that, when dry, forms a rigid covering. The eggs and secretion are known as an egg pod.

The egg pods of grasshoppers vary not only in the number of eggs they contain but also in their size, shape, and structure. A pod can contain from 4 to more than 100 eggs, depending on the species of grasshopper. Grasshopper eggs vary in size, color, and shell sculpturing. Depending on the species eggs range from 1/10th to ½ an inch long and may be white, yellow, olive, tan, brownish red, or dark brown.

Most grasshoppers have laid their eggs by now, and the lingering warmth of the soil is already incubating them. They will soon enter diapause (the suspended development of an insect/insect embryo that occurs during winter in New England) and will resume their development come spring.  (Photo: Grasshopper egg pod & eggs, Penn State College of Agricultural Sciences)

 


Ladybugs Maturing & Seeking Shelter

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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.


Locust Borers Laying Eggs

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The Locust Borer (Megacyllene robiniae) is so-called because its host tree is Black Locust (Robinia pseudoacacia). Locust Borer larvae tunnel into a tree’s trunk and branches, weakening the tree and making it susceptible to wind breakage. In addition, these tunnels serve as a primary infection site for the wind-borne spores of the fungus Phellinus robiniae, which causes a damaging heart rot disease in Robinia species. If you see a Black Locust with many dead and broken limbs, and/or knotty swellings on the trunk, chances are great that it has been attacked by Locust Borers.

The conspicuous, brightly-colored adults appear when goldenrod is in bloom. Adults are commonly seen feeding on goldenrod pollen. Mating takes place now, in the fall, and eggs are laid  in cracks, wounds and under loose bark of a Black Locust tree. The eggs hatch in about a week, the larvae bore into the inner bark of the tree and each larva makes a small hibernation cell and overwinters there. In the spring the larvae begin to bore into the woody part of the tree, enlarging their tunnels as they grow. By mid-summer they pupate and adult beetles emerge in late summer. Previously confined to the native range of Black Locust in the Northeast, Locust Borers have spread with the trees throughout the U.S. and parts of Canada.