It’s cold, wet, windy and not conducive to enticing anything to a black light and moth sheet so that activity’s been curtailed until night temperatures return to around 70 degrees Fahrenheit.
The dreary weather is good for revisiting some of my moth sheet finds. Moths aren’t the only things that are attracted to lights at night. If I’m quick, I can get some good bug shots to upload to iNaturalist.org for identification.
Insect wings are beautiful; there is amazing variety and design to the wings of different insects. In September, a rather unique looking creature came for a very brief visit – a dobsonfly, I found out; iNaturalist.org identified my photo as a pale dobsonfly, Corydalus luteus.
There are some 30 species of dobsonflies in the New World, according to AgriLife extensionentomology.tamu.edu, but only one species in the United States: the eastern dobsonfly, Corydalus cornutus. However, the article goes on to say that there is disagreement, as there are three western species in genus Corydalus, which are currently included under species cornutus.
I went back to the iNat dobsonfly gallery and scrolled through and found pictures of three dobsonfly species: Eastern, C. cornutus, Western, C. texanus and pale C. luteus.
To my untrained eye, the differences seem to be the numbers of tilde-like markings on the wings – a tilde is a squiggle like this: ~ It’s the keyboard key on the upper left – usually under the ESC button on a common “logi.”
Regardless the tilde numbers, Corydalus are large flying insects endemic to North, Central and South America. They are night active and live close to water, generally flowing water. The male has a pair of long sickle-shaped mandibles that resemble ice tongs. Females have shorter jaws, more closely resembling wire cutters, or pincers. Males use mandibles only for defense. My photo is of a female, showing shorter jaws and antennae.
Dobsonflies are among the largest flying insects in Texas. They can be up to three inches long and their wingspan can reach to five inches. The one on my moth sheet was a lovely color of taupe with lighter dots all over its wings. The females lay eggs on vegetation or structures overhanging a source of water. Larvae in the first instar stage drop or crawl to the water.
The larvae are known as hellgrammites and are aquatic predators. They feed on the larvae of other aquatic insect species. They have gills and don’t surface until ready to pupate. Fishermen use hellgrammites as bait.
Adult dobsonflies do not live long and probably do not feed, so lucky me for seeing one at 4:07 a.m. one morning. Neither adults nor larvae are considered a pest, rather they are a beneficial insect. The larvae are a key component in the fish food chain and their predatory nature helps keep other species in check, including blackflies, a serious biting pest, according to extensionentomology.tamu.edu.
The beautiful-winged dobsonfly was a new species for me – so you can see some of the glory of setting up a black light and white sheet and trekking outdoors when most people are sleeping.
A smaller pretty-winged mid-September visitor hung around to just after daybreak one morning. It was tentatively identified in iNaturalist.org, and not yet verified, as an Ichneumonid wasp, Family Ichneumonidae, a family of parasitoid wasps in the insect order Hymenoptera.
Ichneumonid wasps attack immature stages of holometabolous insects (orders that include beetles, flies, wasps, dobsonflies, butterflies and moths) and spiders, eventually killing their hosts. It is posited that parasitoid wasps fulfill an important role as regulators of insect populations, making them promising agents for biological control, according to numerous sites.
As wasps go, most ichneumon wasps are harmless to people, although the female can look intimidating with her long ovipositor. They are active at night and attracted to lights. The adult consumes plant sap and nectar. There are thousands of species of ichneumons in North America, and many are hard to tell apart. Colors vary, some are drab and others brightly colored or patterned; some have the black and yellow bands like stinging wasps.
One of the things I’ve observed many times on a busy moth sheet is that the various species peacefully occupy the same space – they fly in, land, crawl over and around one another with seemingly no gang wars or shoot-outs. One night, I photographed an interesting black and white bug just after dark. When I cropped it in the phone to upload to iNat, I noticed a belted grass veneer moth had hitched a ride on its back; neither seemed to care – just an ordinary night at the moth sheet. The bug was identified as an assassin bug, Microtomus purcis, a North American species in the family Reduviidae.
It’s just as well the moth flew off fairly quickly. I read that this assassin bug has a “very dynamic diet” which includes insects, smaller arachnids, and juveniles of the same species; in turn, it is preyed on by birds, reptiles, some mammals, and larger arachnids. While researching the M. purcis, I was happy to notice a Google photo of one attacking a scorpion.
I recently found a striped bark scorpion in the house. I’m hoping it’s a one off, coming in with a box that had been delivered. This scorpion, according to Wikipedia.org is extremely common throughout the midsection of the United States and northern Mexico. If it’s true, what else I read, that their color suits their environment, providing them with a natural camouflage, then I’m telling myself it’s the color of the box that had just been delivered and we’re not harboring a nest of scorpions.
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