Tuesday, August 26, 2014

Dogbane beetle



What: The end of summer is the time of the insects! I've been watching the dogbane sprout up new shoots, flower, and finally go to seed over the past three months. Because they're a particularly noxious plant (toxic to almost all vertebrates and many vertebrates - they're related to milkweed which is infamous for its implications for monarch caterpillars), they have insects specialized to feeding on them. Similarly, koalas, which exclusively eat the poisonous leaves of eucalyptus, is specialized to eat one and only one thing. The koala's evolutionary trick was to find a way around the defenses of something so toxic that doesn't have any other predators and then exploit that weakness. So too with the dogbane beetle (Chrysochus auratus). Dogbane is a notorious weed in the midwest, largely because it doesn't have any natural pests that control its population.

On the photo at the bottom, I had actually moved it to a milkweed leaf right next to the dogbane where I found it. There were a number of milkweed aphids on the underside. Once the beetle had crawled to the underside of the leaf it kept stomping its feet and then would fly a few inches to a new spot. It seemed really perturbed by the significantly smaller beetles. After about 30 seconds of "torment" it flew to another leaf.


Sunday, August 3, 2014

Gemmiferous

Extensive patch of shining club-moss

What: While out on the Long Trail this week with the Crow's Path Adventurers camp (photos here), I was able to return to a patch of shining club-moss (Huperzia lucidula) I had noticed last weekend while scouting with Sam. The patch is located at the turn off to Silent Cliff, just north of Middlebury Gap. It's been about 5 years since I looked more intimately at the club-mosses (family Lycopodiaceae), and I was struck by the strong patchiness of the plant - some of the patches were a dense carpet of up to about a half acre, and it was a rare site along the trail to see any growing by themselves. I have in my head images of little cones sprouting from the tips of clubmosses, and was delighted that, upon closer inspection, there were no cones at all, but a new mysterious type of leaf.

Flattened gemmae, or vegetative propagules, that act in the same way as leaves on jade plants

Ecological notes: Turns out members of the Lycopodiaceae genus Huperzia lack the cones, or strobili. Plants with this strong of a predilection for patchiness typically have vegetative reproduction (e.g. spread by underground roots like staghorn sumacs), really heavy seeds that don't disperse terribly far, seeds that get dispersed by non-volant insects (like trilliums and ants), or extremely narrow and extreme habitat requirements (like cattails in marshes or Green Mountain maidenhair fern in serpentine outcrops).

Each band of spores = 1 yr of growth
Shining club-mosses lack creeping rhizomes/underground stems, which other clubmosses (e.g. Lycopodium spp.) spread laterally out along or just beneath the surface of the soil, so they need to accomplish this in another way. In this case, the gemmae, those flat, paddle-like leaves (they almost look like elm seeds) are vegetative propagules that fall off the parent plant. They don't have far to fall and so aren't carried more than a few centimeters at most from the parent plant. The new plant is a genetic clone of the parent and in time will create its own gemmae (always at the tips of new growth).

Also, unlike similar relatives in the genus Lycopodium, whose sporangia (spore clusters) are borne on cones that reach up into the air waiting to be whisked away by wind, Huperzia have sporangia borne on leaf axils (the little notch where the leaf sprouts off the stem). In the photo to the right, these are the clusters of yellowish bean-shaped things running short segments up the stem. Each band of spores represents a single year of growth, giving some sense of maturity.

There is scant literature around the lifespan of shining clubmoss. A related species, Huperzia sa, can reportedly take 15-20 years just to reach maturity. So it appeared from my brief look into their world that wind dispersal doesn't play much of a role and their presence in large, thick patches indicates that they've been around for a long enough time for their vegetative parts to create dense mats. Maybe it's even an indicator of at least secondary growth.

Where: Unlike the other Huperzia sp. that we have in our state which grow on rocks, H. lucidulum grows on soils. Its preference for rich - yet acidic - moist soils under a hardwood or coniferous canopy make it a common denizen of higher elevation woodlands.

Wednesday, July 23, 2014

Robber flies

Robber fly eating a small white moth
I've had the fortune of seeing quite a few robber flies this year (I first discovered these guys two summers ago). Though seemingly nondescript, they're among the most gruesome of all predators. Relying on surprise, robber - or assassin - flies, lay in wait for an unsuspecting prey to come along and then ambush them, taking the insect out of midair.

Butterflies, moths, and many other nectar-loving insects have long, spindly and bendy proboscises. Not so the robber fly, whose short and hard proboscis is thrust into the body of their prey. It's hard to make out in the photo, but they have a bristly mustache on their face that is potentially a face mask that protects them as their prey flails about.

Then like a shrew, they inject the unfortunate insect with a neurotoxin that paralyzes it and, like a sea star or spider, follows up with an enzyme that liquefies the prey's innards. From there, they make an easy job of slurping up the slurry of guts.

Friday, July 18, 2014

Peregrines at Rock Point

On April 6, I wrote an email to the Vermont Bird Listserv:
I was out at Rock Point yesterday afternoon when I heard a peregrine falcon! This was exciting enough, but it got even better. I watched it fly out over Apple Tree Bay a couple of times before returning to the cliffs below where we were perched. We then watched it swoop out and hover low and fast over the ice about a half mile out to the fracture line in the ice. Along the fracture (which runs from Lone Rock Point out to Appletree Point) there are a few gaps that have open water.
When the falcon got out to the fracture line it landed and we realized that there was already another peregrine out there. They seemed to be watching the open water, maybe for fish in search of higher oxygen concentration? After a few minutes the same falcon took off and flew back directly towards us, it got to the cliff where we were sitting and started to land before it noticed us. It turned and flew back to the ice, mounted the other bird, mated awkwardly while she slipped on the ice, then flew back about 4 seconds later, as is the economy of mating in birds, before landing at the thrust fault. It continued to shriek, and make return visits to the icy (though never mounted the other bird) for about an hour.



Over the past few months we've been able to watch from a distance the peregrines nest building, hunting off the cliffs, carrying food back to the nest, and now successfully fledging two young falcons! The young are easily distinguished by their incessant screeching and begging. I was able to photograph the dramatic playing of the young as they half-heartedly swooped down at a family of mallards at Mink Bay. 

Wednesday, May 21, 2014

Planties in a bunch


One of the things I relish most are my memories of seeing animals being fallible - like squirrels falling out of trees or beavers tripping. Maybe it's a bit odd (or worse, sadistic), but my enjoyment is in watching the animals suffer, but the reminder that they are animals just like us, prone to error, confusion, mistakes, emotions, and the drive to struggle on.

My powers of empathy extend first to mammals, next on to other vertebrates, and then invertebrates. I can connect with insects, but my connection is not as immediate and often includes a slight sense of awkward self-awareness around empathizing with this clade. My chain of empathy often forgets the plant kingdom (John Berger wrote that we like to look at animals because, unlike them, when we look at them we are aware that they are looking at us in the same way. But the other day while taking photos with one of the kids at Crow's Path, we spotted a most peculiar plant that reminded me that the struggles of life extend to all living creatures.


Unlike most trilliums (trillia?) that push their way through the duff by pushing leaves out of the way, this unfortunate soul got stuck trying to rend its way through a sugar maple leaf. It got all twisted and couldn't quite make it to the unfurling stage. I often see this pattern with Canada mayflower. The plant presses on with development, flowering in this instance, despite the jumble of leaves. Trillium are perennial so potentially the hindrance to photosynthesis will not matter much this year - perhaps next year it may suffer slightly, leaf out later, grow a weaker/shorter stem, etc. Only time will tell.
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