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Sunday, November 1, 2009

Insect IDs

I've had some time to sit down with my new field guide (Insects of the Pacific Northwest by Peter and Judy Haggard) and have been successful in identifying some insects from my photos. There are some cool looking critters to share with you today!

This first one is one of my favorites for its interesting shape and unique coloration. (It was also relatively small at about 10-15 mm long, which made it more pleasant to approach than some of the larger specimens below. I'm not exactly an entomophobe, but I do believe in giving insects their space and hoping they give me mine!) From the shield-like shape I was immediately able to narrow it down to a stink bug (Family Pentatomidae), but the colors looked nothing like any of the photos in my guide. By referencing The Bug Guide, I was able to learn that its actually a stink bug nymph (Chlorochroa spp.):

Some insects, like butterflies, go through complete metamorphosis, progressing from an egg to a larva, then a pupa, then an adult. Others, like stink bugs, go through incomplete metamorphosis, hatching from an egg to become a nymph, then becoming an adult after one or several molts (instars). The fact that you can encounter a wide variety of nymphal stages in addition to the adult stage of an insect will make identification much more difficult, I can tell....

Aside from the charismatic butterflies and moths, the other large, common, distinctive insect group we often encounter is the order Coleoptera - the beetles. My field guide has a nice introduction at the beginning of the beetle section:

Coleoptera is the largest order in the animal kingdom and, with approximately 290,000 species described, contains an estimated 37 percent of all known insect species. More than 23,700 species have been recorded in the United States and Canada. Approximately one-third of the total number of insect species found in the Pacific Northwest are beetles.

This first beetle, pictured above, is a golden buprestid (Buprestis aurulenta) of the metallic wood-boring beetle family. In addition to its remarkable iridescent coloration, notice the four longitudinal grooves that run down each wing, another identifying mark.

The next one, pictured below, is a tiger beetle (Cincindela spp.). There are several similar species that vary in how green/brown the body are as well as the particular yellow markings on the wings, so I'm not sure which particular species this is. The field guide notes that they can be difficult to approach, and indeed this one was running when I saw it. This is the only photo I was able to get of it - I'm lucky it turned out as well as it did!

This next beetle I at first thought was either a ground beetle (big and black) or stag beetle (large jaws), so I was surprised to figure out that it was also in the tiger beetle family, although in a different genus. This is the flightless tiger beetle (Omus audouini). The mouth parts are what I immediately noticed, but upon closer examination I also looked at the shallow pits on the wing covers.

Moving on from beetles, here is a common fall critter that I've always heard referred to as a woollybear caterpillar. Turns out this is accurate - its a larval banded woollybear (Pyrrharctia isabella), that will eventually metamorphose into a tiger moth. According to an old wives' tale, the width of the orange band in the middle will tell you how cold the upcoming winter will be. Hmm, this band doesn't seem to be too wide - are we in store for a milder winter than last year?

Here is another closely related species - the larva of a rangeland tiger moth (Platyprepia virginalis). It's funny that I recognize many of the tiger moth larva, but not the boldy patterned adult moths.

There's nothing quite like picking up a new field guide and, while flipping through it, finding something that I haven't been able to identify anywhere else. As I've expanded my horizons over the last year and a half from birds and marine mammals to also encompass wildflowers, mushrooms, and insects, I've experienced this joy of identifying a new species several times - they are very much "Ah-ha!" moments. This last photo was one of those moments, the very first thing I identified using my new book - and I didn't have it down as being insectoid at all!

I thought this was some kind of fungal parasite when I found it growing on these plant leaves this summer. Take a look:

It's actually a gall formed by a gall wasp (Family Cynipidae). They're tiny wasps that are hard to find or identify, but each species lay their eggs on a particular host plant, and as a result a distinctive looking growth (the gall) develops in which the larva feed. The galls are the easiest way to detect and identify the species. The one pictured above is the rose leaf gall (Diplolepis polita). So THAT'S what that thing is! Amazing.


The K said...

Cool selection of critters. I really like the legs of the tiger beetle. Learned a lot from this posting. Thanks.

Warren Baker said...

I often ID things from books Monika. The trouble is i forget them just as quick. I can't hold things in for very long. :-)

Lancashire and Lakeland Outback Adventure Wildlife Safaris said...

Thanks Monika. Excellent stuff - love the tiger beetle know what yu mean about tryin to collar them ours flit along the trail movin on just as you get em in focus - nightmare!



Heather said...

A very educational post. Every year I add a few more field guides to my collection, and insects and mushrooms are next on the list. I really enjoyed learning about these critters from you. I know what you mean about those "Aha!" moments. I'll come across wildflowers in my flower field guide that I photographed years ago, only just know finally figuring out what they are. It's fun stuff!