Glamorous Moths #5 – Penstemonia

The way that gardeners feel about moths and butterflies is often quite different, despite how closely related they are. We are happy to grow milkweed to attract Monarchs and allow the caterpillars to devour whole plants. Weed is in the name milkweed, so I think we value the plant more for its role in the Monarch’s life cycle. On the other hand, who ever heard of growing corn to attract Helicoverpa zea or tomatoes to encourage Manduca sexta?

Perhaps the most despised moth is the peach tree borer, which “bring major harm to important fruit-crop trees, destroying the tree’s vascular system through boring and girdling while inducing plant pathogens to invade the weakened tree” (Source). That’s terrible, right? How dare those selfish moths cripple our precious fruit trees?

Without further ado, I would like to introduce the Penstemon clearwing, also known as the Beardtongue borer.

Penstemonia clarkei, Clarke’s Penstemon clearwing, seen in Los Alamos, New Mexico

Penstemonia is a genus of moths in western North America (presumably including northern Mexico) in the family Sessiidae (clearwing moths). [Quick sidenote: Hemaris clearwing moths are in the hawk moth family, Sphingidae.]

Clearwing moths often resemble wasps and bees in coloration and marking. They have elongate wings, often transparent owing to the lack of scales. Most of the larvae are borers in the limbs, trunks, bark, or roots of trees, shrubs, herbs and vines (like the infamous peach tree borer). Some bore in galls on woody or herbaceous plants. Majority of adults take nectar. [Source: bugguide.net]

What about our Penstemon clearwing? 

There are at least 5 species of Penstemonia in North America. Larval feeding is probably limited to Penstemon or closely related plant species in Cheloneae. (I’ve discussed Penstemon plants on the blog before: https://pollinatorweb.com/meet-the-plants-more-beardtongues/). The larva will be found within a stem [or roots] at crown level and damage appears as a wilting or dieback of individual stems. Pupation is probably in the soil at the base of plants, but there is no description of them. [Source: Colorado State University Extension (colostate.edu)]

I have a feeling that populations of Penstemonia moths will start to increase and spread as more gardeners grow native, drought tolerant beardtongue plants. I hope you will welcome these pollinators into your yards with open arms.

Leave a Comment

Your email address will not be published.