Is it just me…

…or does this jumping spider look like it’s driving a truck, with its left hand on the wheel and its right arm dangling lazily out the window?


It had taken up residence in a dragonfly naiad’s shed skin along the shore of a pond on Nantucket.


That’s all I wanted to say about that.

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Walnut Caterpillars

Last August I was invited to the Polly Hill Arboretum on Martha’s Vineyard to give a presentation about my insect research on Nantucket. After the slideshow I led a walk around the arboretum in search of insect tracks and signs. It’s always a little challenging to show the tiny things I focus on to a large group of people, but right outside the barn where I gave the presentation, there was a striking bug-related phenomenon I hadn’t encountered before: a big ball of hairy caterpillars hanging from a branch of a black walnut tree.


The caterpillars had devoured all the leaves on some parts of the tree.


Some mature caterpillars had dropped to the ground and were wandering off in search of a place to pupate. On close inspection, they didn’t look like anything I recognized.


Then I noticed some immature ones that were still feeding. Their stripes and posture (abdomen bent upward) reminded me of the genus Datana (Notodontidae).


So I grabbed the arboretum’s copy of Dave Wagner’s Caterpillars of Eastern North America and opened to the Datana section. Sure enough, the first species I saw was D. integerrima, which has been given the common name of “walnut caterpillar.” I gather from Wagner’s remarks section that the caterpillars had collected into that dense cluster in order to molt. Apparently I didn’t bother to take a photo of it, but I seem to remember looking the next day and seeing that all that remained of the caterpillar ball were some shed skins hanging in the loose webbing.

I was going to make this post a miscellaneous collection of things I found on Martha’s Vineyard, but upon rereading Wagner’s notes on Datana integerrima just now I realized that the mystery moth eggs I found nearby were in fact D. integerrima eggs: “The white eggs, small for a prominent, are deposited by the hundreds in one or more adjacent rafts—each egg bears a small black central spot.” (Members of the family Notodontidae are generally referred to as prominents.)


What had caught my attention about these eggs, apart from being something distinctive that I didn’t recognize, were the tiny parasitoid wasps that were emerging from them. Fortunately they were still emerging the next day when I got around to bringing out my macro lens.


Having reared identical wasps from eggs of a tawny emperor butterfly (Nymphalidae: Asterocampa clyton), I recognized these as male eulophids in the subgenus Tetrastichinae, though I have no idea what genus they might be. I mostly encounter (very different-looking) tetrastichines as parasitoids of gall insects, but some of them parasitize leafminers.

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Sunflower Tortoise Beetles

Another one of my winter projects, of course, is sorting through all of my photos from last year. So far I’ve made it up to July 15, when Julia and I had just arrived in Iowa to explore some prairie remnants on our way home from Colorado. Our first stop was Hayden Prairie, where some unusual beetle larvae caught my eye. They were all feeding on what we determined was sawtooth sunflower (Helianthus grosseserratus).


You may have noticed that in the above series of photos, each larva is wielding a larger “club” of wet poop than the previous one. This habit made them easily recognizable as larvae of tortoise beetles (Chrysomelidae: Cassidinae), although I’d never seen the “poop shield” take quite this form before.

Looking around, I found the egg mass from which some of them had emerged:


And then I found a beautiful adult tortoise beetle, which I assumed to be the same species…


…until I saw this totally different one on the same host plant:


I was wondering which adult beetle went with the larvae until just now, when I searched for the host plant on BugGuide and discovered that all of the above photos depict Physonota helianthi, a.k.a. the sunflower tortoise beetle. The website gave no explanation for these two radically different adults, but I pulled out my trusty copy of Art Evans’ Beetles of Eastern North America, expecting to learn which is the male and which is the female… but he explains that “freshly emerged adults are dingy white, then turn black and white for about 3 weeks before reaching maturity as a brilliant metallic green beetle.”

So there you have it. On BugGuide there is an interesting series of photos showing a female constructing an egg covering, which apparently consists of a framework of silk covered up with some kind of goopy secretion. Those photos were taken in Massachusetts, not far from where I live, which makes me wonder why I’ve never encountered these beetles before.

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Progress Report

Today I reached a major milestone in my leafminer book project: I’ve now made keys to the known leaf mines on every plant genus in the US and Canada. To do this, I had to review the published natural history information for 35 sawfly species (one of which I co-described last year), 200 beetle species (three of which were just described in the most recent issue of the Coleopterists Bulletin, in addition to the Orchestomerus species I discussed in my last post), over 500 fly species, and over 1000 moth species (these last two groups have many more described species that are almost certainly leafminers but have never been associated with any host plant). I include these parenthetical asides to highlight the fact that this project can never really be finished, because more species and life histories are being discovered all the time.  But I’ll consider it to be time to start looking into publishing this thing when I’ve finished writing all the introductory chapters, which could conceivably happen by the end of this winter.

The last keys I wrote, after finishing all the graminoids (grasses, sedges, and rushes), were the ones for all the conifer needleminers. I was dreading these all along, because I didn’t think there could be much variation in needle mines and wasn’t sure how I could construct keys to them. But luckily T. N. Freeman spent over 30 years studying needle-mining moths and made some keys in the 1960s that I was able to build on. It was actually sort of fun working out how, for instance, 30+ species of moths might be distinguished by their idiosyncratic styles of living inside pine needles.

So I thought I’d celebrate by sharing photos of a couple of conifer needleminers from my own front yard. As shown in the photo at the top of this post, when Julia and I first moved here there was literally nothing in the front yard except for a lawn and an arborvitae (a.k.a. northern white cedar, Thuja occidentalis) hedge along the road. Five species of moth are needleminers on Thuja, and so far I’ve found two of them in our hedge. The mines all look pretty much like this:


If you backlight the mines from our hedge, you can see that they are all nice and clean-looking because the larva (which is curled into a “J” in the photo below) has been pushing all of its frass out of a hole at the tip.


Only two of the five arborvitae miners are fastidious in this way, and they can be distinguished by the color of the larva.


Since this larva is brown, we know it’s Coleotechnites thujaella (Gelechiidae). I raised some adults this spring, and when I took one out to the hedge to get a natural-looking photo of it, I found lots of them hanging out on the foliage already.


A number of Coleotechnites species can only reliably be distinguished by the habits and host plants of their larvae. When I sent one of these adults to Jean-François Landry to confirm that it was C. thujaella, he annotated my tentative identification with “reasonable id BUT others possible.” At this point, no other Coleotechnites species is known to feed on Thuja, so I’m going with that ID until someone comes up with a reason to question it. In terms of wing pattern, there are probably more differences between the two individuals above than with some individuals of other species of Coleotechnites.

Along with the Coleotechnites adults, there were a number of these hanging out on the hedge at the same time:


This is Argyresthia thuiella (Argyresthiidae), a member of a family that has been given the common name of “shiny head-standing moths.” It happens to be the other species that makes nice, clean, frass-free mines on arborvitae. Its larvae are green instead of brown, and I didn’t happen to notice any last spring, but theoretically I should be able to find some right now, since these needleminers all overwinter in their mines.

In the process of rearing the Coleotechnites larvae, I also had a bunch of tiny (1 mm) parasitoid wasps emerge, all in the family Encyrtidae. To my knowledge no one has ever suggested a common name for encyrtids, but they’re a good deal shinier than “shiny head-standing moths,” for whatever that’s worth.


Copidosoma lymani (female).


Copidosoma lymani (male).


Copidosoma bucculatricis (male).

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Virginia Creeper Weevils, Revisited

You may recall that last year I wrote about an interesting weevil I found one day while at work in some horrible swamp in southeastern Massachusetts. Or rather, what I found were pairs of mysterious yellow larvae mining side by side in Virginia creeper (Parthenocissus) leaves…


…and a few weeks later they revealed themselves to be adorable little weevils.


I explained in my previous post how weevil expert Bob Anderson had identified them as Orchestomerus wickhami, how I wrote up an account of their natural history for my first ever scientific paper, and how shortly afterward Bob informed me that they weren’t O. wickhami after all. I promised I would report back when this was all sorted out, and when I opened the new issue of the Coleopterists Bulletin today, I discovered that that day has arrived.

In their review of the genus Orchestomerus*, Hiraku Yoshitake and Bob Anderson have determined that there are four species in North America. A few months after I sent Bob my weevils, he happened to collect a series of O. wickhami adults in Brownsville, Texas, where the type specimen of that species had been collected. When he dissected males from Texas and compared their genitalia with those of mine from Massachusetts, he realized that they were separate species.

After examining many specimens from all over the US, Yoshitake and Anderson found that only specimens from the southern tip of Texas represented true O. wickhami, which is associated with sorrelvine (Cissus trifoliata), another member of the grape family (Vitaceae)All other specimens that previously would have been identified as O. wickhami are in fact members of a new species, Orchestomerus eisemani. This is apparently the most common and widespread member of the genus, ranging from Texas and Florida north to Kansas, southern Ohio, and Maryland… and then there is a seemingly disjunct population in Plymouth County, Massachusetts, where I collected those larvae and someone else had caught a female in a malaise trap in 2006.

Adults of the other two species have both been associated  with grape (Vitis). Orchestomerus whiteheadi is known from southern Arizona and New Mexico. The other species, now known as O. marionis is named for the type locality: Marion, Massachusetts, which also happens to be in Plymouth County. It has otherwise been collected in Missouri, Indiana, North Carolina, Mississippi, Georgia, and Florida. It has a confusing taxonomic history: Dietz had described O. ulkei in the same 1896 paper in which he described O. wickhami and the genus OrchestomerusAuleutes marionis was described in 1913 and later synonymized with O. ulkei, but it turns out that the type specimen of O. ulkei was actually a specimen of Auleutes epilobii, a species associated with the evening primrose family (Onagraceae). Auleutes marionis in fact belongs in the genus Orchestomerus, so Yoshitake and Anderson resurrected the name marionis and transferred it to Orchestomerus.

I was able to make a last-minute contribution to their study by providing them with some additional specimens Tracy Feldman and I reared from larvae he collected in North Carolina this spring. Two of these are pictured below, in a photo that gives a better sense of their smallness.


Although it’s clear that all four species are associated with the grape family, it remains to be determined whether the larvae of the other three are leafminers. So far Orchestomerus eisemani is the only known North American leafminer in the weevil subfamily Ceutorhynchinae. In Europe, two Ceutorhynchus species mine leaves of mustards and related plants. There are many North American Ceutorhynchus species associated with mustards, so there may be some leafminers lurking among them that no one has noticed yet.

Added 1/21/2016: Here is a map showing the known distributions of the four Orchestomerus species.

* Yoshitake, Hiraku and Robert S. Anderson. 2015. A review of the genus Orchestomerus Dietz (Coleoptera: Curculionidae: Ceutorhynchinae: Cnemogonini) of the USA. The Coleopterists Bulletin 69(4): 565–578.

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Introducing Megaselia nantucketensis

In my ongoing survey of gallmakers and leafminers on the island of Nantucket, I have been trying where possible to verify the identities of these insects by actually rearing them to adults. And so in May of 2012, I collected a bunch of black and scrub oak leaves (Quercus velutina and Q. ilicifolia) with midge galls that I was pretty sure were caused by Macrodiplosis niveipila based on Ray Gagné’s 1989 book, The Plant-feeding Gall Midges of North America. They consisted of swellings along veins, with fuzz-lined longitudinal slits on the upper leaf surface to allow the mature larvae to exit.


Within a few days, the little white larvae came squirming out of the galls, and when I moved them to jars of soil they quickly burrowed down.


The following April, several adults emerged (about 3 mm long).


I sent them to Ray Gagné (along with assorted other gall midges), and he had this to say about them:

The Macrodiplosis females you reared from oaks cannot be identified further. What further identification would require is an exclusive and at least three-year project collecting galls from all the oaks east of the Mississippi, retaining some larvae and rearing adults from each kind of gall and host.  Basing Macrodiplosis identifications on anything less than that would just be guesswork.

So we’ll stick with “Macrodiplosis sp.” for now. But some other things emerged from the same jars of soil, within a few days of the midges, and I had better luck getting them identified, although it took me a while to find someone who could do it. Two of them were platygastrid wasps, which I sent to Peter Neerup Buhl in Denmark.


This one, about 2 mm long, is Metaclisis floridana. It has never been reared before, so there’s no telling how host-specific it might be.


This one, about 1 mm long, is a Synopeas species. Because I just had this one male specimen, Peter was unable to place it to species with confidence, but it might be S. pubescens, which likewise has never been reared.

As far as is known, all platygastrids in the subfamily Platygastrinae are parasitoids of gall midges, so it was not surprising to find these tiny wasps coming out of the jars. It was surprising when this zippy little scuttle fly (Phoridae) appeared (about 2 mm long):


In my ignorance, I had thought of scuttle flies as mostly generalist scavengers, but it turns out the larvae of this genus (Megaselia) have extremely diverse habits: in addition to scavengers, there are specialized predators, parasites, and even herbivores.  Two have previously been reared from galls: M. submarginalis from the boxelder gall midge Contarinia negundinis, and M. chainensis from the elm cockscomb gall aphid Colopha ulmicola*. In both of those cases the Megaselia larvae are specialized predators, devouring several aphids or midge larvae before completing development.

I sent the fly off to scuttle fly specialist Brian Brown at the Los Angeles Natural History Museum, and he reported that it didn’t key out to any of the described North American species. A year later, he informed me that Emily Hartop, who has been focusing on the genus Megaselia, had taken it through every other key in the world and determined that it is a new species. So Emily and I named it Megaselia nantucketensis, in a paper that was theoretically published in October but just today showed up online**.

There are plenty of Megaselia species left to be found. Earlier this year, Emily described 30 new species that were caught at 30 sites right in Los Angeles, inspiring articles in the New Yorker, the Washington Post, and elsewhere. You can read Emily’s own account of their discovery here. What makes M. nantucketensis unusual among these discoveries is that we have some idea of what it does for a living, although there is certainly more left to learn there too.

* Robinson, W. H. and B. V. Brown. 1993. Life history and immature stages of two species of Megaselia (Diptera: Phoridae) predatory on gall-inhabiting insects. Proceedings of the Entomological Society of Washington 95(3):404–411.

** Eiseman, Charles S. and Emily A. Hartop. 2015. A new species of Megaselia Rondani (Diptera: Phoridae) reared from a Macrodiplosis Kieffer (Diptera: Cecidomyiidae) gall on black oak. Proceedings of the Entomological Society of Washington 117(4):463-466.

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Silk on Stink Bug Eggs, Part 2

In my last post I wrote about a little wasp in Mexico that apparently spins silk over stink bug eggs after it inserts its own eggs inside them. Several people had told me confidently that it was a pteromalid, so I went with that. However, shortly after I published my post, Henry Hespenheide wrote:

I think the parasitoid is a eurytomid.  Note the very large pronotum which is characteristic of the family.  And a number of the genera have the wings infuscated like the ones you show.  One of the subfamilies, Rileyinae, are egg parasitoids.

To be honest, I had thought it looked like a eurytomid too, but “it kinda looks like a eurytomid” is about as sophisticated as I get in identifying micro-wasps before appealing to someone else for help. What I was seeing, besides the general shape, was that it was rough-textured and black, just like most of the eurytomids I’ve reared from galls. For instance the one below, which came from a goldenrod rosette gall made by a fruit fly (Tephritidae: Procecidochares):

IMG_4806 That one had been having trouble getting the antenna portion of its pupal skin off, but had just succeeded in removing the right “sleeve” when I took that photo.

Anyway, I guess the fact that I had only ever encountered eurytomids as gall parasitoids had kept me from considering that this stink bug egg wasp might be one. But as pointed out here, eurytomids have a wide variety of habits, and many even have vegetarian larvae that develop in seeds or stems. In fact, here is one I found in my yard this spring, a member of the genus Tetramesa, whose larvae are known as “jointworms” and cause galls in grass stems.


I only just learned that a few weeks ago, but my brain is so full of leafminers right now that everything else gets pushed out. Speaking of which, some eurytomids in the Neotropical genus Aximopsis are parasitoids of leaf-mining beetles (Buprestidae).

Anyway, I followed Henry’s advice and showed my last post to Mike Gates, the eurytomid specialist at the Smithsonian National Museum of Natural History. Mike confirmed that the wasp in Cheryl’s photos and videos is a eurytomid in the genus Neorileya, and said he would be interested in seeing specimens. He has never heard of Neorileya producing silk, and is interested in more concrete proof that this wasp was actually responsible for the silk, since we can’t actually see the wasp laying down silk in the videos, nor was Cheryl able to see silk coming out of the tiny wasp.

To me, the fact that Cheryl photographed the wasp on the egg mass over a period of several days, during which the silk covering gradually increased, is pretty convincing. There’s also this: right after I published my last post, Kelly, who had sent the photo of the original silk-covered egg cluster from Brazil, wrote to tell me that she had found another silk-covered stink bug egg cluster with a similar wasp on it:


Unfortunately the wasp flew away after she took several pictures, but she collected the egg mass and will save anything that emerges from it. Stay tuned…

Edit: Kelly just found another photo of a similar wasp taken in Brazil, here. As with Kelly’s photo above, the silk is in bands that stitch the eggs together, rather than covering them in a web as in Cheryl’s example from Mexico.

The photographer, Bruno Garcia, gave me permission to use his photo here, but if you want to see a larger version you can click the above link.


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