More and more

Adults have emerged from another 20 or so overwintered vials and jars since my previous post. Here are some more that came from larvae collected right in my yard.

On June 21, I collected these larvae from one of our cultivated hazelnuts (Sawfly #27 in this post):

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Thirteen of them reached maturity and burrowed into a jar of soil by the end of the month. Over the past few days, three of these wasps have emerged from the soil:

They appear to be braconids in the genus Ichneutes (thanks to Gergely Várkonyi for the ID). In my decade of rearing all sorts of herbivorous insects, to my knowledge I have only previously reared two braconids in the subfamily Ichneutinae, both from tiny leaf-mining moths. The ichneutines that parasitize sawfly larvae oviposit in their hosts’ eggs, or sometimes in young larvae, but their offspring wait until the sawfly larvae have finished feeding and spun their cocoons before doing most of their own feeding and ultimately killing their hosts. Did the mother Ichneutes manage to insert an egg into every one of these hazelnut larvae (or the eggs from which they hatched) before I got to them? Time will tell.

Last year’s Leafminer #89 was Stigmella prunifoliella (Nepticulidae), which I identified based on a predated leaf mine on black cherry that I found on June 26. On September 28 I collected a few leaf mines on peach that I presumed were the work of this species, but I wanted to make sure since it hadn’t been documented on peach before. Here is a very early mine, with the green larva munching away inside…

…and here is a vacated mine three days later…

…and here is the adult that emerged on March 22:

Virtually all of the insects I have emerging right now are univoltine species, with just one generation per year, and larvae found only in spring or early summer. With the exception of some parasitoid wasps, Stigmella prunifoliella is the only multivoltine species that has made an appearance so far.

Last year’s Sawfly #25 was a larva I found in June on white avens (Rosaceae: Geum canadense)…

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…and within a few days I found larvae that I thought might be the same (though I noted a behavioral difference), feeding on leaves of cultivated strawberries.

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On March 22, an adult emerged from each jar—strawberry…

…and avens:

I still think they might be the same! I believe the only sawfly in North America with free-living larvae that have been found on avens is Pristiphora pallidiventris, and this clearly isn’t that. I’m guessing this is one of the six species of Allantus, Empria, and Taxonus that are known to feed on strawberry, but I won’t worry about which species that might be just yet. [Edit, 3/26/2021: Marko Prous says these are “Empria (maculata maybe, which seems to be a complex of several species)”.]

Early last June I pointed out a gall on a fox grape leaf made by Heliozela aesella (Heliozelidae), an odd species in a family that (in North America, anyway) is otherwise composed of leafminers. Here is a better look at one of the galls, viewed from above and below:

The mature larva cuts out an oval chunk from the upper surface of the gall and wraps it around a tube of frass held together with silk, then wanders off, dragging this portable burrito-house until it finds a suitable place to overwinter, at which point the gall chunk becomes its cocoon.

On March 22 two of these emerged as adults:

While I was putting together my “Bugs in Winter” course, I cut open some goldenrod stem galls from my yard so I could include photos of their interiors in one of my slideshows. When I cut open this gall of Epiblema scudderiana (Tortricidae) in January…

…I found the live moth larva still inside (as would be expected for this species), visible in the photo below through a little nick in its protective silken tube.

Since it would likely be doomed if I put the opened gall back outside, I instead put the gall in the fridge along with the other overwintering bugs, and took it back out with the rest of them on March 1. Alas, it turned out the larva had already been doomed by parasitoid larvae living inside it: eleven of these microgastrine braconid wasps emerged on March 22:

Based on this study of parasitoids of Epiblema scudderiana, these wasps might be Apanteles cacoeciae, which was the only microgastrine and the only gregarious parasitoid associated with this moth in western Pennsylvania.

Back on May 29, I found my second type of sawfly larva for the year, a member of the Acordulecera dorsalis complex (Pergidae) feeding on red oak.

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The seven larvae I collected all burrowed into soil by June 3, and three adults emerged on March 23 and 24.

All the ones from my yard, and another five I reared from a red oak sapling across the road, look like the one above—not as fancy as the ones I reared from the same host in Connecticut five years ago:

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And finally, there was the leaf-rolling sawfly larva (Pamphiliidae) that I found on June 7 on one of the shadbushes we planted by our garage:

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The adult emerged yesterday, a lovely wasplike creature:

About Charley Eiseman

I am a freelance naturalist, endlessly fascinated by the interconnections of all the living and nonliving things around me. I am the lead author of Tracks & Sign of Insects and Other Invertebrates (Stackpole Books, 2010), and continue to collect photographs and information on this subject. These days I am especially drawn to galls, leaf mines, and other plant-insect interactions.
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2 Responses to More and more

  1. Bob Kipfer says:

    Bob Kipfer here, you have helped me in the past for Identification etc. for our blog at http://springfieldmn.blogspot.com/. We teach weekly at the 5th grade WOLF School and are always looking for nature activities for the students at home as well. What technique do you use to raise sawflies etc. over winter.

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