Eggs, Caterpillars, Stinkbugs and Laternflies

Top Photo: Hummingbird moth (Hemaris thysbe) egg on viburnum flower buds (shiny, round, green object).

Hummingbird moth eggs are very small, about 1mm – 1.5mm. To see one of those swift flying, diurnal moths lay an egg requires being in the right place at the right time. Standing next to a viburnum (frequent host plant for this species) is a good place to be. I’m not sure of the right time, though a bright sunny summer’s day seems about right.

The egg in the photos was deposited by a moth just as I, and two other rangers, were chatting about the wildlife we’d seen so far that day. And yes, we were standing quite close to several viburnums. The moth buzzed one of the plants, stuck out its abdomen when its sensors signaled it was the right place and time to lay its egg, and pasted a single shiny green egg to an emerging flower head on the popular landscaping shrub. We were lucky.

Hummingbird moth egg. Inset: adult hummingbird moth.

On the same viburnum, several days later, we spotted an unknown species of stinkbug. A quick search resulted in the bug being ID’d as an anchor stinkbug (Stiretrus anchorago).

Anchor stinkbug.
Named for the pattern on back.

The anchor stinkbug pictured happens to have a pink pattern over blue-green iridescence. The pattern can, however, be red, yellow, orange, white, and more, with variations in the pattern shape.

Anchor stinkbugs are predators of mostly leaf beetle larvae and caterpillars. It’s probably not a coincidence that this stinkbug showed up where it did, there are many larger elm leaf beetle larvae skeletonizing our various elm trees’ leaves and orange-striped oakworms munching on our scarlet and willow oaks on the outdoor loop trail.

Adult larger elm leaf beetle.

Adult larger elm leaf beetles, which are native to our area, lay their eggs on the undersides of elm leaves. When the eggs hatch the larvae immediately begin to skeletonize the leaves. When sufficiently fed,“The mature larvae crawl down the tree and undergo a wandering phase for a few days before entering the ground.” They’ll remain underground until the following late winter or spring. After pupation, which takes about a month, the adults finally emerge from the ground, beginning the cycle over again.

Larval larger elm leaf beetle.
Leaf almost completely skeletonized,
Elm leaves in leaf litter along path.

Though it’s stated in reports I’ve read that “The mature larvae crawl down the tree…,” I’ve personally witnessed several of them free-fall to the pavement, dust off and crawl away. They move very slowly. It would take many hours (a day’s worth) to crawl down out of the elms I’ve seen them munching on. Once on the ground, however they get there, they head off in whatever direction they land.

Curiously, I’ve not seen birds attempt to pick them off either the ground or leaves. Even so, many that drop to the pavement don’t make it to the safety of the leaf liter on the side of the path. As mentioned, besides being very slow, they’re inconspicuous and most areas around the outdoor loop are high traffic much of the time.

Larva crawling to some unknown location to burrow in ground for winter.

Are there smaller elm leaf beetles? Yes. The elm leaf beetle (Xanthogaleruca luteola) is an introduced species which can be found over much of North America. It originated in Europe. It too consumes elm leaves. I’ve yet to encounter one here at the museum.

As happens each year around this time, orange-striped oakworms are chowing down on several oak trees along the outdoor loop trail. They’re most easily observed in Catch the Wind where they can be seen both chewing the leaves of the trees and attempting to crawl safely across the path. Once they reach their final larval stage the caterpillars drop to the ground and seek a secure location to burrow into the soil. They’ll remain there as pupae until the following spring/summer.

Oakworms in early stage of larval development.
This oakworm will soon crawl off to pupate.

The trees of choice for the oakworms here at the museum are scarlet and willow oak.

A caterpillar that I don’t see on a regular basis at the museum is the milkweed tiger or tussock moth (Euchaetes egle) larva. They appear to me as a walking jumble of yarn, a very shaggy, unkempt appearance, a mini dog chew or pull toy.

The caterpillars eat milkweed and dogbane, which makes them toxic to those who would eat them, birds. Their appearance may tend to ward off would-be predators. While its said they feed gregariously, I usually see them alone.

The scruffy milkweed tiger moth caterpillar.

Another caterpillar that’s likely to be encountered by itself is the 3 inch, or more, rustic sphinx moth caterpillar. The one pictured was on Buddleia, though it will eat many diverse plant leaves, from common sunflower to beautyberry.

Rustic sphinx moth caterpillar hangs over Butterfly House steps railing.

The spikes or “granules” on the head and horn help identify this large green larva.

Hanging on by its prolegs.
Rustic sphinx.

Towards the end of July, I heard a local TV news story about spotted lanternflies (Lycoma delicatula) confirmed as being seen in North Carolina. The laternflies were observed about four counties west of Durham County in the town of Kernersville.

Spotted laternflies are true bugs. They’re in the Order Hemiptera which puts them in the same group of insects as cicadas, planthoppers, and aphids, plant-sucking insects all.

The news story went on to say the insects were destroying vineyards, orchards, ornamental plantings and other vegetation wherever it was found. The invasive insects were first detected in Pennsylvania in 2014 and have been observed in 11 other states since.

Adult spotted lanternfly.

The insect’s host plant is tree of heaven (Ailanthus altissima) which, along with the lanternfly is native to China and other parts of east Asia. Besides its host plant, laternflies are known to feed on at least fifty six other plants in North America.

I had never seen a spotted lanternfly until the first week in August when I was on a road trip through Pennsylvania. I pulled into a gas station to fill up. When I got out of the car it was evident that something was amiss. There were large gray, red and black insects everywhere, on the pump, the ground, everywhere. Having seen the news story about this brightly colored menace, I knew right away what I was looking at, spotted lanternflies.

The locals thought something amiss with me as I excitedly went about snapping photos of the insects, while they went about crunching the bugs under their feet.

A nymph, final stage before adulthood.

I wish I’d gotten more photos. The locals, however, were eyeing me with increased suspicion the more excited I became. Time to top off and head out.

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