A Stigmella moth leaf mine in a bristly blackberry leaf.
While out one afternoon in my tamarack swamphunting for dwarf mistletoe, the subject of a future post, I found this leaf mine in the leaf of a bristly blackberry. The blackberry is possibly Rubus flagellaris, but I’m still working out the identity of the species.
The leaf mine bears a strong resemblance to the leaf mines made by the larvae of the moth Stigmella villosella (Family Nepticulidae). Stigmella villosella is a specialist on Rubus species. The adult moths are minute with a wingspan of only 3 mm.
I doubt I’ll see this moth at my lights, but maybe next year, if I find an active leaf mine, I could raise the larva to maturity. I’m going to give it try anyway.
Another Rubus leaf, but without leaf mines, just a few holes all near the midvein made by some unknown insect.
It might be getting colder outdoors, but there are still insects to be found. While out walking a few days ago, I came across this odd growth on a Dryopteris cristata (crested wood fern) frond.
This tightly coiled knot on the frond is caused by a galling insect that specializes in ferns. The species responsible for the gall is a fly (Diptera, Anthomyiidae) named Chirosia betuleti.
The fly’s larvae form galls on several fern species: Athyrium filix–femina (lady’s fern), Dryopteris carthusiana (spinulose wood fern), Dryopteris cristata (crested wood fern), Dryopteris filix–mas (male fern), Matteuccia struthiopteris (ostrich fern), and Pteridium aquilinum (bracken fern).
A search for other galls the next day located one empty gall on the frond of a Dryopteris carthusiana plant in a tamarack swamp. I looked for Athyrium filix–femina and Matteuccia struthiopteris, but their fronds had already withered away now that it is fall. I’m sure I’ve seen these odd growths on them before. None of the Pteridium aquilinum plants had galls, and I don’t recall ever seeing them on the fronds before. There’s always next year.
Dryopteris carthusiana with gall
Gall formation
The larvae of Chirosia betuletifeed on the trichomes (hair-like growths) along the midrib of the newly emerging frond, and then mine along the midrib, causing it to coil into a mophead shape.The related Chirosia grossicauda forms galls on bracken fern. Another insect to watch for next year.
The Anthomyiidae
Chirosia betuleti is a fly in the family Anthomyiidae (root maggot flies). Most species in this family feed on plants as larvae, feeding on roots, seeds, or mining leaves.
Some feed on dung, decaying plant matter, or mushrooms. Other species are endoparasitoids of grasshoppers, and some are kleptoparasites of Hymenoptera.
Adults feed on nectar and pollen and may be pollinators. Most species resemble small houseflies.
Range
Chirosia betuleti is reported on iNaturalist from the western coast of North America from Alaska to California, and inland to Saskatchewan, Canada, and Idaho, and Montana, around the Great Lakes and New England, then east to the Maritime Provinces of Canada. The range then follows the Appalachian Mountains south to the Great Smoky Mountains. There are two isolated occurrences in South Carolina and Florida.
Parasites of Chirosia betuleti
Larvae of Chirosia betuleti are parasitized by wasps in the genus Aphaereta (Braconidae) and the wasp genera Dimmockia and Elachertus (Eulophidae).
Big-leaf aster (Eurybia macrophylla) in bloom out in the woods.
It is the first day of October, but it doesn’t feel like it. Our temperatures are in the high 70s, and the warm weather will continue at least until Sunday. So I decided to look for any flowers that might still be blooming on this unseasonably warm autumn day. Although there is not a profusion of flowers this far into autumn, some still can be found.
Two that are still in full bloom are showy goldenrod (Solidago speciosa) and trumpet weed (Eupatorium fistulosa). These two plants are always pollinator magnets, and today they were loaded with bumblebees, syrphid flies, and wasps.
In an earlier post, I wrote about Lophocampa maculata, a moth in the Arctiinae, distinguished by its fuzzy black and yellow larvae. These larvae later metamorphose into beautiful adult moths with a contrasting pattern of alternating bands of warm, muted golden-orange and darker brown markings with a reddish-orange tinge. In this post, I write about Halysidota tessellaris, the banded tussock moth, another moth in the Arctiinae.
Halysidota tessellaris caterpillar feeding on a crabapple leaf in late summer.
Identification
Like Lophocampa maculata, the larvae of Halysidota tessellaris are also fuzzy, but they are usually gray to dingy brown with long white and long black tassels. The adult moth, while similar in size to Lophocampa maculata, has translucent yellow forewings marked with slightly darker bands and irregularly shaped block-like cells that form a tessellated pattern. Also, there are two parallel blue stripes on the fuzzy thorax.
Life cycle
Across its range, larvae of Halysidota tessellaris feed on many species of hardwood tree leaves. Among these are box elder (Acer negundo), sweet birch (Betula lenta), ash (Fraxinus spp.), oaks (Quercus spp.), and many others. Adult moths take nectar and are pollinators of milkweeds (Frost, S. W. (1965) Insects and Pollinia. Ecology, 46. 556-558, paywall).
Halysidota tessellaris, a worn specimen, but the blue lines are prominent.Halysidota tessellaris showing the tessellated pattern of the forewings.
Similar species
Adults of the related Halysidota harrisii (sycamore tussock moth) are similar in appearance to Halysidota tessellaris. Where the ranges of Halysidota tessellaris and Halysidota harrisii overlap, genital dissection is necessary to determine the species. Halysidota harrisii larvae, which may be solid white, yellow, orange, or gray, feed exclusively on sycamore (Platanus occidentalis) leaves. The ranges of sycamore and the moth coincide closely.
Not Very Far Away 