Archive | September, 2011

Meal Time

30 Sep
Crab spider eating a mirid.

Crab spider devouring a web-wrapped plant bug (Miridae).

Just a random picture of a crab spider with a mirid lunch all wrapped up.  Plant bugs seem to be a popular lunch item in my neck of the woods. Of course, they’re the largest true bug (Hemiptera: Heteroptera) family, mostly herbivores, and conveniently snack-sized.

Herpetology, I love you

26 Sep

On the topic of unusual critters that show up in my house, I found this teeny little rough earth snake chilling out on my bedroom rug.  Despite the fact that I was just posting about the giant water snake on my back doorstep this is actually pretty unusual for me.  For the most part, I can’t even manage to find these guys under logs and in leaf litter where they’re supposed to be.

As far as I can tell the timeline went something like this:

6pm:  I share a comic on Facebook with the comment, “Herpetology, I miss you.”

10pm:  Herpetology misses me back.

Scarabs: The Green June Beetle

23 Sep
Large green squarish metallic iridescent june beetle.

A green june beetle (Scarabaeidae: Cotinis).

Here’s a beetle that my dog, a budding canine entomologist, chased down and caught for me on our walk the other day. These big, metallic green beetles are one of the more striking insects we see in the area.  This fellow was out a bit late in the year, so it was fun to see one.

Much like the brown june beetles (or “junebugs”) that mob my porch in the summer, adult green june beetles are attracted to lights.  The adults feed on fruit and sometimes flowers (they are a significant vineyard pest), while the grubs shelter in the soil during the day and emerge at night to feed on vegetation and roots (they can be a minor lawn pest).  Apparently these grubs have the unique habit of crawling on their backs, using short stiff hairs rather than their legs, which is a cool fact I did not know.  Two characters of note for this genus are the horn-like projection of the mouthparts and the way in which the pronotum (first plate of the back) extends to a point, covering the scutellum.

As a side note, it is extremely difficult to capture metallic and iridescent coloration on camera (I lack the appropriate combination of equipment, patience, and skill).  Ted MacRae of Beetles in the Bush has some good comments on the subject, and just generally takes gorgeous tiger beetle photos.

Thorn Mimics & Other Freaks of Nature

16 Sep
A thorn-mimicking tree hopper on a branch (Membracidae).

A thorn-mimicking treehopper on a branch (Membracidae).

Membracids (commonly called treehoppers) are one of my favorite bugs–and one of the few smaller insects that I will consistently take the trouble of snagging for my collection.  At the start of my journey into entomology I can recall being deeply impressed by some thorn-mimicking treehoppers pointed out to me on a branch.  They look like thorns!  They run around the branch and try to hide from you!  They hop!  What’s not to love?

Oh, and a good number of membracid nymphs have mohawks.  That’s pretty freaking adorable, right there.

These little guys are incredibly diverse.  Here’s a picture that’s not mine:

Morphological variation in membracid helmets.

Variation in treehopper morphology (Photo credit: Prud’homme et al 2011).

Not only are there thorn-mimics and brightly colored aposematic hoppers, but also feces and even ant-mimics.  The treehoppers that look as if they have sprouted entire mutant ants from their back are some of my favorites.

Now, I was taught that this structural diversity came from variations in the pronotum, but it turns out membracids are even more interesting than that.  Recent research has provided evidence that the helmet structure is actually a novel appendage, entirely unique to the genus.  This structure is apparently something like a modified third wing, the presence of which may be a result of mutations to the Hox gene complex.   (This is the same group of regulatory/developmental genes that can cause mutant flies to sprout legs in the place of antennae and such.)  A very cool example of evolution in action!

See also: Ants & Hoppers

The Mummy – Aphids and Parasitoid Wasps

2 Sep
The remains of a parastized aphid mummy complete with wasp larva escape hatch.

The remains of a parastized aphid ("mummy") complete with parasitoid escape hatch.

My labmate Collin found mummies in his aphid colony.  It was kind of exciting, although maybe not up to horror movie standards.  Mummies are what happen to aphids when a parasitic wasp injects them with an egg.  As the wasp larva grows inside their bodies, feeding on their hosts, the still living aphids swell into pale, bloated, unmoving forms on the leaf surface.  Eventually, adult wasps burst from their hosts, leaving behind the kind of gruesome sight pictured above.

Close up of cotton aphid (Aphididae) feeding on cotton leaf.

Close up of cotton aphid (Aphis gossypii) feeding on a cotton leaf.

For comparative purposes, here are pictures of a healthy, live aphid, as well as the shed skin of an aphid following a molt.  For a frame of reference these guys are about a millimeter or two long.

The shed skin of a cotton aphid (Aphis gossypii).

Cotton aphid exuvia (cast off exoskelton) on a cotton leaf.

Special thanks to Collin McMichael for helping me with the digital microscope photography.  And thanks also to someone who featured a how to on manual focus stacking in photoshop a while back.  I cannot find this post again for the life of me.  There was a picture of an ant with a parasitoid I think.  It was awesome.  I have been wanting to try this technique for a while, so it was fun to experiment.  I should probably get a shot with the legs in better focus in the future.