Dogwood Hole Punchers

In anticipation of driving across Iowa last September, I asked John Pearson for some suggestions of places to stop and explore.  Thanks to him, I saw some interesting little prairie relics and a fen that I never would have found otherwise.  My favorite place was the Loess Hills area at the west end of the state.  The “loess” of which the hills are composed is a fine sediment, created by glaciers and deposited by wind after the glaciers receded.  This roadcut offered an opportunity to see a cross-section of one of the hills:

The darker material toward the bottom is vegetation creeping up the cliff; the sediment is pretty uniform all the way down.  There was an interesting mix of plant species in the Loess Hills, including some that I normally associate with floodplains growing alongside others that are typical of dry, rocky uplands.  When investigating a patch of roughleaf dogwood (Cornus drummondii), I encountered some blotch type leaf mines that puzzled me at first.

Holding a leaf up so that it was backlit, I could see a moth larva chewing away inside–but the discrete, elongate pellets of excrement ruled out most things I could think of.

After a little more investigation, I realized what I was looking at.  In the completed mines, the larva had cut out an oval leaf piece and wandered off to pupate.

This identified the miner as a member of the family Heliozelidae, known as the “shield bearers” because the larva wears the leaf piece like a shield, ultimately attaching it to a twig or some other surface and pupating within it. I had tried several times but had never succeeded in raising a heliozelid to adulthood, so before running to the nearest clump of trees to shelter from a sudden thunderstorm, Julia and I stuffed a vial with leaves that still contained larvae.

When I took all my rearing vials out of the fridge last month, I didn’t have much hope for these since the leaf material had more or less turned to mush and was growing mold, but lo and behold, a few days ago this beautiful 3.4-mm moth emerged.

There are three described dogwood-mining Antispila species in North America.  One is only found west of the Rockies; one feeds on bunchberry (Cornus canadensis) and other northern dogwoods of damp habitats; I presume this is the third, which is found from Ontario to the Gulf Coast and feeds on southern, upland dogwoods: Antispila cornifoliella.

Here is this moth’s leaf “shield,” with the empty pupal skin protruding from the left side.

John Pearson was kind enough to look through my photos of unidentified Iowa plants and tell me what everything was (including the roughleaf dogwood).  I’ve now gotten as far as uploading all of my Idaho plant photos, and if anyone out there knows their South Dakota / Wyoming / Idaho plants well, I’d be grateful if you would check out my flickr page and leave some comments with suggested identifications.  All of these plants have leaf mines associated with them, many of which are likely new to science.

Golden Saxifrage

This month I’m conducting surveys for four-toed salamanders throughout northwestern Massachusetts, and after spending some time crawling through swamps I feel inspired to showcase one of my favorite early spring wildflowers.  Golden saxifrage (Saxifragaceae: Chrysosplenium americanum), also known as water carpet, is common in seepy areas throughout New England.  I don’t know much about it beyond that, but I suspect its tiny flowers are overlooked by most people, and I like the way the bright orange anthers are arranged in little squares.

The flowerbuds, too, are in the form of neat little square packets.

Here’s a more zoomed-out view of the plant:

The flowers are only out in the spring, and the rest of the year the plant just looks like this:

Monthly Mystery #6: Manzanita Scrapings

A few weeks ago I was sent the photos below, with these comments:

I found it on the bark of manzanita (Arctostaphylos) in Napa County, California on March 31. . . It resembles feeding sign of a rabbit because the scrapes go down to the cambium, but is in horizontal rows and goes too high up on the branches. It has no clear incisor marks either. I know some insects tunnel through the bark of trees and shrubs, but this looked like scrapes from a chisel or nail. The scrapes were about 1/8th inch wide, parallel, horizontal, varying lengths, and sometimes left short strips of bark hanging off the ends.  

My response was: “If this is an insect sign, the closest thing I can think of is nest material collecting by paper wasps, hornets, etc., but in my experience they always strip parallel to the grain of the wood and use weathered wood rather than fresh bark.  Also I have never seen so much stripping so close together.  I’ve seen nest material gathering by squirrels, mice, etc. that looked superficially similar, but as you pointed out there don’t seem to be any incisor marks.”  Anybody out there have any further insights?

Fairyfly

Today I happened to see this article just as I was getting ready to try to photograph a “fairyfly” (Mymaridae) that had emerged from a Bidens alba (romerillo or common beggarticks) leaf I’d collected a few weeks ago.  Lacking a scanning electron microscope, I did the best I could, and of 124 photos taken in the course of 15 minutes, the four below were my favorites.  At half a millimeter long, this wasp is twice the size of the newly described Tinkerbella nana.  It is actually the second mymarid to emerge from that leaf, which I collected hoping to raise the leaf-mining agromyzid fly larvae it contained.  I’m not sure if any mymarids are known to parasitize leafminers; I had always heard that they are all egg parasitoids.  Scouring the leaf under a microscope failed to reveal whatever minute holes these wasps had emerged from.

Egg on a Leaf-footed Bug

On March 17, the night before embarking on the southeastern road trip from which my car has yet to return, I noticed a tachinid fly egg on the head of a Western Conifer Seed Bug (Coreidae: Leptoglossus occidentalis) in my bathroom.

A tachinid fly egg on a true bug (suborder Heteroptera) is likely to belong to the genus Trichopoda, members of which are known as the feather-legged flies.  Having never encountered one of these (or, at least, never photographed one), I figured I’d take the opportunity to try to raise one, so I put the bug in a jar with some soil and went to bed.

To my surprise, the bug was still alive a couple of weeks later, but finally it gave up the ghost, and on April 10 I discovered the puparium of the tachinid larva that had been developing inside it all along.

The moldering bug was lying on its back, and I presume the hole at the tip of its abdomen (shown at right in the above photo) was made by the exiting fly larva.

Yesterday the adult fly emerged.  After browsing through photos on BugGuide.net, I’m fairly sure it’s Trichopoda pennipes.  Since this species is evidently often found on flowers of goldenrod, asters, and the like, it seemed reasonable to set it on a dandelion for a little photo session.  When I was done I left it there to finish warming up and then go forth and find some other bugs to parasitize.

In this side view, you can see why it’s called a feather-legged fly.

I’ve never photographed a fly face from this angle before.  That mouth is pretty vile.

Other angles are a little more flattering, but flies are pretty alien-looking up close no matter which way you look at them.  Still, if they’ll help cut down the Western Conifer Seed Bug population in my house, I’m happy to have them around.

Leaf-footed Bug Egg

One day in south central Florida, Julia and I were walking along a trail through a hardwood hammock when I spotted a beautiful leaf-footed bug (Coreidae) egg.  While I was admiring it, I heard a loud buzz overhead, and I looked up to see a large leaf-footed bug alight several feet above us.  Julia managed this shot of it with the 20x (or so) optical zoom on her little point-and-shoot:

The photo was good enough to identify it as Acanthocephala declivis, a decidedly southeastern species.  I thought it was reasonably likely that the egg belonged to the same species–it certainly looked like an Acanthocephala egg.

It was getting late and we had lots of exploring to do, so rather than take the time to assemble my macro setup, I collected the egg and photographed it in the tent that night.

The next night, the bug had developed (or the eggshell had cleared) sufficiently that what had seemed like fancy decorative markings on the egg could now clearly be seen as body parts of the nymph developing inside.

This top view shows the antennae stuffed into the apex of the egg (it’s difficult to capture in a two-dimensional photograph, but Acanthocephala eggs are vaguely triangular in cross-section).

I was going to try and get a shot every day until it hatched, but things got too busy.  Four days later, the egg was next in line to be photographed after a recently emerged leaf-mining moth, and when I grabbed the vial I discovered that I had just missed seeing the bug hatch.

I’ve always been puzzled why the circular lid that a hatching leaf-footed bug pops off its egg doesn’t correspond with what seems to be a nice ring of perforations at the anterior end of the egg.  True bugs don’t have chewing mouthparts, so they just have to push their way out.

In any case, this bug was another impressive contortionist.

Spider Parasitoid

I have much too much going on right now to be writing blog posts, but I’m waiting for an oil change at the moment, so let’s see what I can do…

On the first night of our road trip we camped in eastern South Carolina by a small oxbow pond from which enormous fish were constantly leaping out and splashing back in.  In the morning we wandered around nearby to see what leaf mines there were to be found, and I spotted something I had seen before in pictures but never in person:

It was a mature larva of an ichneumon wasp in the Polysphincta genus group, which had finished sucking the life out of its spider host and was now hanging in the web, with the spider’s carcass dangling below it.  (I had seen very young larvae before, as shown in the last photo here, but this was the first time I had seen a mature larva with those distinctive leglike projections.)

My past attempt to raise a parasitized spider had failed, but to raise this larva all I had to do was throw it in a vial and wait.  A few days later we visited Troy Bartlett, and I asked his opinion on this spider with green-tipped legs.  He suggested an immature male Giant Lichen Orbweaver (Araneus bicentenarius), and when I posted a photo of it on BugGuide, Lynette Schimming independently made the same suggestion.  I’m not aware of another viable candidate, so it seems likely that’s what it was.

The larva was lying motionless every time I checked on it, but then one day it had spun a loose cocoon at the bottom of the vial.

(My car was ready at this point, but I’m so close, might as well just finish it.)

Two and a half weeks after I collected the larva, this brightly colored wasp emerged:

Since it was so distinctive and I already knew from its natural history that it was a member of the Polysphincta genus group, I tried out BugGuide’s browse function and quickly found a clear match: Acrotaphus wiltii.  The single example on BugGuide of a reared specimen of this species is here–a wasp that found itself trapped inside a mud cell after the spider that it parasitized as a larva was abducted by an organ pipe mud dauber, which used the spider to provision its nest.  I gather from Bob Carlson’s comment there that the only known host of A. wiltii is Neoscona arabesca, the Arabesque Orbweaver, which this spider with green-tipped legs clearly was not.

In the cocoon photo above, the larva had not yet pupated.  If I remember correctly what Howard Ensign Evans wrote in Wasp Farm, all wasp larvae have the same habit of saving up all their excrement until just before pupating and then expel it all at once.  In the case of this ichneumon, the excrement was pushed outside the cocoon, as can be seen in this photo taken after I removed the empty cocoon from the vial: