Wednesday, July 27, 2011

Whence a caterpillar crossses your path

I came across a caterpillar today that was too cool to pass up sharing. You're in for a treat.

I was walking to the science center on campus today and looking around the fringes of the grass, as per usual, when I spotted a caterpillar on the sidewalk. It was serendipitous because I was just thinking about how as an entomologist, I've been training myself to focus on small things and watch for movement that might be overlooked by someone who doesn't constantly look for bugs. It was an interesting moment.

I noticed a small green thing that looked like a leaf, and at first thought it was. A breeze had just blown some leaves across the path, but this was a little different. It's a good thing I don't have a habit of crushing leaves, or this story would be sad.

Sidewalk is not its natural habitat.

A-ha! My first thought: "Definitely not a leaf." My second thought: "Sphingidae." This caterpillar has very pretty colors, like a grape popsicle shoved into a lime. The first thing to notice after the colors is the horn at the end of its abdomen--that's an identifying feature for the sphinx moths, family Sphingidae. Sphingidae is easily one of the coolest (if not THE coolest) families of moths, and they're easily identified by the posterior horn that the caterpillars have. (Unless you're dealing with Abbot's Sphinx - Sphecodina abbottii. In that case, the caterpillar will be staring right back at you with its raised knob that resembles an eye.)

Hemaris diffinis - Snowberry Clearwing
This Sphingid caterpillar is the Snowberry clearwing, Hemaris diffinis, which turns into a beautiful moth. When it reaches that stage, it will have clear wings (hence the common name) and look similar to a bumblebee. How cool is that? Notice the black dots around the spiracles on the side of the caterpillar, and how the horn changes colors from yellow to black towards the tip. Marvelous! While I was moving the caterpillar (first by stick, but when it wouldn't cooperate, just by picking it up), I turned around and noticed another person coming up the sidewalk behind me, looking at me like I was crazy. I tried to explain that I was moving a caterpillar so that it wouldn't be squished, but I'm pretty sure it didn't make me seem less crazy to him.
This is a common occurrence in my life. 

Friday, July 22, 2011

Science Video Friday: Invasive species are a nuisance

Invasive species: from North America to New Zealand to Antarctica, they're a problem. Invasive species, when transported to a new environment, have the capacity to overwhelm the ecosystem and throw it off the natural balance that has been reached by the indigenous organisms. This causes severe damage to the ecosystem, and can have many unforeseen consequences: among them local extinction of native organisms and even increased flooding due to increased storm water runoff.

Here in Southeastern Ohio, some of the more common invasive organisms I see are Tree of Heaven (Ailanthus altissima), Japanese honeysuckle (Lonicera japonica), and the dreaded Japanese knotweed (Fallopia japonica). From what I've seen, Japanese honeysuckle and knotweed are especially nasty invaders, and can take over forests and other areas without prejudice. In the case of Japanese knotweed, it spreads via rhizomes, making it even more difficult to eradicate. One of the major problems of invasive plants, and also the reason why they can propagate so efficiently, is that they don't have many insects that feed on them. The native insects don't have the machinery to digest the invasive plants like they do for the natives, so the invasives spread without much stopping them. Some insects do feed on these invasives, but it's not to the extent of the number that feed on them in their native environment.

Interestingly enough, I've observed Japanese beetles (Popillia japonica) feeding on the leaves of Japanese knotweed. Unfortunately, Japanese beetles themselves are an invasive species, so that's not really a solution to the problem.

While much of what's published on invasive species is about their detrimental effects on the environment, they're not all bad. As discussed in this article from Penn State University, some invasive species can have positive effects for birds. Unfortunately, this positive effect is inconsequential when compared to all the harm invasive species bring to the environments they colonize.

While many of the examples I used were invasive species native Japan, it of course doesn't mean that that is the only place our invasives come from. We have invasive species from all over the world, these examples were just the most well-known to me. Besides, our indigenous North American species have become invasive on other continents as well. Ah, globalization!

Wednesday, July 20, 2011

The Wheel Bug Emerges

I came home today to the most wonderful surprise I've had in a long time:

Arilus cristatus, the wheel bug, in all of its salmon-colored glory.

For those of you who aren't familiar with my love of this particular insect, the wheel bug is my absolute favorite insect. Why? To list a few reasons, it's an assassin bug, it's the largest terrestrial true bug (Order Hemiptera) in North America, and it has that ridiculously interesting cogwheel protuberance on its pronotum. This bug is unique and when you see it, you know what it is and that you shouldn't test its patience.

The fresh new bug on the left, with its out-of-style skin on the right.

Anyway, what we're actually looking at here is the wheel bug right after it has molted out of its 5th instar. Wheel bugs go through a nymph stage of life with five separate growth periods (instars), and it sheds its skin between each period, growing as it does so. At the end of its fifth instar, it has finished its nymph stage and emerges as a fully-formed adult: with wings and its characteristic cogwheel. This wheel does not appear in any of the nymphs. If you're lucky and can catch the wheel bug soon after it has molted its final larval skin, you're in for a treat. It emerges as a beautiful red/pink/orange color....let's call it salmon. 

The wings still have a leathery sheen to them, and are clear enough that you can see the white and red-striped abdomen.

Unfortunately, this salmon color doesn't stick around forever, and fades to jet black within a few hours. Though I suppose in the long run, it's better for camouflage reasons. It's not as striking as the red of course, especially after its yellowish-gray pubescence overtakes its body, but it's functional.

If you want more information on wheel bugs, you can check out a previous post of mine here. 

Monday, July 11, 2011

Cedar Bog....well, it's a fen

This weekend placed me in Dayton, Ohio for the Midwest Native Plants Conference. It was beyond spectacular and I was bombarded with new information everywhere I turned. The conference committee was gracious enough to award me with a scholarship to attend the conference, so I tried to squeeze all the information I could out of the three short days the conference took place. The conference was very well-planned and went smoothly, by the end of the weekend I was exhausted. Really though, I would make sure all my weekends were filled with biology like this one if I could.

The conference hosted some amazing speakers, particularly Steve McKee and Jim McCormac. Steve talked about Botanical Detective Work and his adventures with searching for plants in Richland County that haven't been looked for in over 100 years, which lit a fire under me to go explore Washington County some more. It's amazing what can slip under our noses due to simply not paying attention to what's growing (or crawling!). Jim gave a talk about hummingbirds and the ones we're likely to see in Ohio, very neat stuff. There were some beautiful pictures included to boot.

On the last day of the conference, Sunday, everyone split up into small groups to head into the field. My particular group headed to Cedar Bog, south of Urbana, and I lucked out with who else joined the group: Steve and Jim were both there, with Jim leading it, and we also had Cheryl Harner and Nina Harfmann. The group was in very capable hands. Essentially, if we passed by a plant, one of them would know what it was. Needless to say, I was writing down names like crazy.

Now, Cedar Bog is actually a fen. What's the difference? A bog is acidic, low in minerals, and doesn't really drain. A fen, however, is fed by water, neutral or alkaline, and supports more than Sphagnum moss. But, it was called a bog before it was recognized as a fen, so the name sticks.

Anyway! We found a massive amount of plants and animals during our trek, and it was extremely rewarding. It was the best use of a morning I've had in quite a while. By the end of it, I had taken pictures of 59 different species. That's pretty darn good, I'd say. Having said that, it's time for some pictures.

She has all her limbs, it's just a weird angle, don't worry!

 This beauty descended on a single strand of web and hung around long enough for us to get some nice shots of her. It's a female dark fishing spider, Dolomedes tenebrosus. You can tell it's a female from the sheer size of it: males are smaller. Due to their size, they can take out some pretty sizable prey.

This guy's tricky.

 What at first looks (and sounds) like a bumblebee is actually a robber fly, family Asilidae, Laphria species. Robber flies can be quite large and are vicious when they take down their prey. This one is a bee mimic, which is pretty evident, and if you want to know more about its mimicry, head over to Jim's blog: he's written a good summary of it. Robber flies are my favorite example of why it's important to pay attention to insects. You might think it's a common insect at first, but if you look closer, you'll often be surprised. Something I always look at when I hear a loud buzzing sound from an insect is the eyes. A robber fly's eyes will be very different from what you're used to seeing on a bee's body, so that's the quickest way to separate them. This one happened to be at eye level and caught me off guard after I turned away from the fishing spider. I scrambled for my camera and it flew off the leaf, but thankfully it landed on another one nearby. I'm glad I didn't scare him off, especially since I had already let an assassin bug get away from me a few days before, and later this day a tortoise beetle would escape from my lens. You can't win them all, but when you win one of these huge charismatic flies, you feel a bit better.

This is Michigan lily, Lilium michiganense, and just too beautiful to pass up. This picture turned out very well, and it's such a treat to run across a flower as vibrant as this one.

So that's where the Valentine's Day heart comes from.

Our group reached an open area in the fen and was taken aback by the plants and insects we found hanging around in the sun. I saw my first  Elfin Skimmer, Nannothemis bella, darting around, and also these Seepage Dancers, Argia bipunctulata. The dragonflies were much tinier than what I'm used to, which was super cool. Both species are endangered, making Cedar Bog a very important place for the survival of these two species. 

 Female Nannothemis bella, a wasp mimic not only in color, but in movement.

I still have 54 species to cover, so this Midwest Native Plant Society/Cedar Bog story arc will be elaborated upon in future posts, for sure. The diversity of the place is astounding, it still wrinkles my brain. If you haven't been there before, make sure to add it to your list, it's well worth the trip.