The great thing about being a scientist is that you have more adventures than anyone else! Today I took along the kids from the Lone Star Adventure Camp on a bug hike at the Trinity River Audubon Center, exploring the insect (grasshoppers in particular) diversity of the area around Catttail Pond. Earlier in the summer when I did bug hunts with YMCA camps, I had noticed that the grasshoppers caught near the building (where we have a lot of switchgrass and Sideoats gramma) seemed to represent a different population than the ones caught some twenty yards away, where the area was mostly Johnson grass. It'd be difficult to collect a pack of adults willing to go hike in the sun for 90 minutes to check out this idea, but kids -- ah, kids are up for adventure, sun, and catching cool bugs.
And off we went, armed with nets, holding cages, and enthusiasm!
I had noticed earlier in the summer that the sheer number of grasshoppers in the switchgrass area at TRAC seems to be smaller than the ones in the Johnson grass area. Some areas of the Johnson grass section are predominantly (90% at a rough estimate) differential grasshoppers (Melanoplus differentialis.) They're huge, fat, and sassy grasshoppers -- mostly gray-yellow with bright yellow abdomens. There's the occasional two striped grasshopper (Melanoplus bivittatus) and Two-lined toothpick grasshoppers (Mermiria bivittata http://bugguide.net/node/view/202024/bgimage) and gray bird grasshoppers (Schistocerca nitens), but the bulk of them are just differentials.
The first few catches in the new area started confirming my hunch. We found that the dominant species was the Two lined toothpick grasshopper, which was about 70% of the total catch. The second most frequent catch was the Red-legged grasshopper (Melanoplus femurrubrum), while differential grasshoppers were a distant third. We caught a very few gray bird grasshoppers as well, and a beautiful little fifth instar Two Striped Grasshopper with exquisite thoracic patterns like the one shown here: http://cirrusimage.com/orthoptera_two-striped.htm
Of course, being with kids means you get to see some things you might miss. One of them showed us how to gently drop sand into antlion holes so that the larva would lunge quickly (in a little fountain of sand), thinking there was an ant around. I did see a single Clouded Sulfur butterfly by Cattail pond, and we saw a beautiful Tiger Swallowtail butterfly and Black Swallowtail. We caught a male Pondhawk dragonfly, noticed a number of Widow Skimmer dragonflies, and noted that the predominant species over by Cattail pond seemed to be the Black Saddlebags dragonflies. And on the way back in, Scott presented us with a lovely large wolf spider with black forelegs -- a check through the bug guides shows that this is the
Rabid Wolf Spider - Rabidosa rabida -- and the black legs means it's male.
All in all, a delightful morning -- and there's nothing like trying to identify species in the field to make you aware of how much more you wish you knew!
There are, of course, a number of other questions that this preliminary survey brings to mind -- such as whether birds prefer to NOT eat the differential grasshoppers that have been feeding on Johnson grass and what the exact proportions of the species are. But the initial results are very interesting as a starting point for other research -- so thanks to the kids at the Lone Star Summer Camp (from the Dallas Arboretum) who came to Trinity River Audubon Center and helped me hunt bugs!
...you know, I could have NEVER found a bunch of old folks who would have been so happy to charge around in the hot sun and help me catch grasshoppers!
