Color in the field!

As spring rains give way to warm, sunny days, the meadows of Mount Rogers come to life with the emergence of a plethora of insects. Among these creatures is a beetle with a striking iridescent blue body and a yellow-orange wash across its elytra (forewings). The elderberry borer beetle (Desmocerus palliatus) also has knots running up its long antennae, lending to its alternate name, cloaked knotty-horned beetle.

This species of long-horned beetle is an obligate specialist, requiring elderberry plants for larval development. Eggs are laid near the base of the stem. After hatching, larvae burrow into the stem and down to the root system. Here, they feed until they are ready to form a pupal cell in the pithy stem tissue. Maturation takes two years. As soon as the mature female emerges in the spring, her scent begins to draw in males and mating takes place immediately.

This individual was spotted near a cluster of elderberry plants in a Konnarock meadow.

Very distinctive, the elderberry borer was featured on a US postage stamp in 1999.

Is it a yellow jacket wasp or not?

Whenever an insect lands on you, it is time to pay attention and figure out if there is going to be a problem! Is there going to be a bite or sting or just a tickle with no further consequences?

I recently noticed a scary-looking small bug on my leg while biking and decided to check this out since it strongly resembled one of our most feared wasps, the yellow jacket. Now yellow jackets are not to be trifled with as I have learned several times when I have had to deal with their formidable nests. They are fierce and have a strong sting and an attitude to boot. On closer inspection I realized that although this bug (see photo of syrphid fly) is a close mimic of the yellow jacket wasp, it is in fact a fly. How did I figure that out? I look at the wings and can see that there is only one pair of wings (wasps have two which fold back). The eyes in flies are larger and placed differently and the antennae are shorter. If you can see the mouth, flies have sucking or piercing mouth-parts whereas wasps have chewing mouth-parts. Flies also behave somewhat differently - for example this bug was drinking sweat from my leg- in an apparent attempt to pick up some salt/sodium which is lacking in their mostly herbivorous diet. With some practice you will be able to make this distinction too, so do not just dismiss the swarm of bugs flying around you in Summer-time, have a look at them carefully and pick out the pretenders from the real bad dudes.

Now just when you have the flies separated from the wasps, along comes another yellow and black critter (see photo of locust beetle) which is not uncommon in our yard since we have a lot of black locust trees. This is an entirely different type of insect (a beetle instead of a fly or wasp), yet it is colored rather similarly and seems to be also mimicking a yellow jacket to obtain protection from predators. Birds likely recognize and avoid yellow jackets and their mimics which fosters the evolution of such convergence in color and pattern. This does not work on mammals such as skunks which make a good living by digging out and eating the young found in the nests of yellow jackets. Indeed skunks, which themselves are well protected by scent and advertised by a striking color, are highly thought of in our neighborhood by farmers who value them for their ability to destroy yellow jacket nests which can cause a lot of pain during haying time.

So learning the basics of insect identification can pay dividends not only in terms of protecting your own hide, but will add to your understanding and enjoyment of the natural world.

Bill Dunson

Galax, VA & Englewood, FL

Those bodacious beetles

In my wanderings among the woods and fields I often encounter beetles, which are not usually considered among the most colorful of the insects, as are the butterflies. However there are some striking exceptions to this rule, one of which I call the "jewel of the forest," the six-spotted tiger beetle. This little gem is an iridescent green of the most amazing hue (see photo) which is accentuated by its habitat in sunny gaps in the forest. These little monsters are truly tigers at their scale and run amok among the tiny insect denizens of the forest floor. Although I will be quick to point out the adaptive advantages of many color patterns, I am at a loss to provide any definitive answer for this distinctive green flash. Obviously it makes the beetle more visible to predators with color vision (birds), but the speed and alertness of this tiny tiger may negate this factor. Indeed it might even confuse a predator since the green wing covers are lifted during flight. The color is not a sexual attractor since both sexes are green. So we are left with another of nature's many mysteries.

Another impressively colored beetle is the dogbane beetle (see photo) which has an amazingly iridescent "coat of many colors." Such rainbow-like patterns are normally produced by a series of tiny grooves that diffract light, not by pigments. This beetle feeds on dogbane which is a close relative of milkweed and has a similarly milky and toxic sap. So it is likely that this beetle is advertising a toxicity derived from its food. Such an advertisement is common among a group of insects that feed on milkweed, including the red milkweed or four-eyed beetle (shown here mating- and note the double eye- hence the scientific name Tetraopes tetrophthalmus). Isn't it interesting how birds recognize that red-orange advertises toxicity in insects, but that red fruits are ripe and yummy?

So while you are out and about in nature watch for those very numerous beetles (the most species diverse of any kinds of animals) and contemplate the purposes, not to mention the beauty, of the many different colors and patterns that they possess.

-Bill Dunson

Galax, VA & Englewood, FL