Tag Archives: Insect

Big Galls on Big Sagebrush

Early last spring, driving along the road past “The Elbow”—that sharp bend in the East Walker River that touches the northeast edge of the Bodie Hills—I was struck by the abundance of large galls on the branches of big sagebrush (Atremisia tridentata subsp. tridentata) beside the road. They were the size of walnuts to small apples.

Sagebrush galls

A bit of searching about galls on sagebrush led me to a post by Jonathan Neal on the Living with Insects Blog, which identified these as galls of the sponge gall midge (Rhopalomyia pomum, in the gall midge family, Cecidomyiidae).

Sagebrush galls

These tiny, delicate flies lay their eggs on the stems of big sagebrush. When the larvae hatch, they chew on the plant and chemicals in their saliva induce the growth of these large, soft-spongy galls on the stems. The larvae continue to grow and feed on the interior of the gall. With some luck, adult midges will emerge and renew the life cycle. Unlucky midge larvae may become hosts for tiny wasps. Wasps in Eulophidae and Platygastridae (and probably other families) are parisitoids (parasites that ultimately kill their hosts) that will lay their eggs in the developing midge larvae within the galls. The wasp larvae consume the midge larvae, and adult wasps, rather than adult midges emerge from the gall.

Sagebrush galls

Welch (2005) surveyed the literature and found mention of at least 42 midge and aphid species known to produce galls on big sagebrush. Many other insects and arthropods are associated with sagebrush in various ways. Not to mention the birds, mammals, fungi, and even lichens that will live in an area only because sagebrush is a dominant species. This all illustrates how sagebrush can be a “foundation species“—one that has a strong role in structuring a community and makes it possible for many other species to exist wherever it grows in abundance.

Reference: Welch, Bruce L. 2005. Big sagebrush: A sea fragmented into lakes, ponds, and puddles. Gen. Tech Rep. RMRS-GTR-144. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 210 p.

Copyright © Tim Messick 2016. All rights reserved.

Hemileuca Larvae: Do Not Touch!

On a recent hike near Carson Pass in Alpine County, I encountered this critter crawling vigorously across a dry swale in the subalpine dwarf-shrub steppe at 8,900 feet.

Hemileuca heraHemileuca hera larva

It was about the size of my little finger and was about to disappear under an Eriogonum, so I coaxed it onto a stick and moved it to a large rock, where I took pictures while it resumed its ascent toward Red Lake Peak. The spines all over its body made it look about as fun to handle as a cholla cactus or porcupine, so I used the stick to prevent any direct contact.

That was a good thing, because on doing an image search in Google and checking further on Butterflies and Moths of North America and Bug Guide, I narrowed it down to Hemileuca hera, the Hera buck moth or Sagebrush sheep moth. The larvae of Buck moths and the related Io moths (both Saturniids) are well known for the extremely painful, persistent, burning, swelling stings produced when the spines inject their toxin into your skin.

Hemileuca habitatHemileuca hera habitat

An article on the University of Florida’s Featured Creatures site advises that “Not handling caterpillars that have spines is one of the best ways to avoid receiving stings.” Obvious, but sensible advice. Should you, however, inadvertently come into contact with one of these beautiful creatures, the wound should be treated by “washing the site immediately in order to remove any loose spines that might be present. The site should be allowed to dry without the use of a towel. Any remaining spines should then be removed with an adhesive such as duct tape. Finally you can apply ice packs to the site to relieve some of the pain.”

Hemileuca hera has been seen in the Mono Basin and it ranges across much of the Intermountain region, so it is likely to be present in the Bodie Hills. The larvae feed on sagebrush. The adults have striking white and black patterns on their wings.

Copyright © Tim Messick 2015. All rights reserved.