Thursday, September 25, 2014

Seven September Days

Every once in a while I’m fortunate enough to see something interesting on seven consecutive days – if I don’t it’s not because there aren’t a lot of interesting things to see every day, instead it's because I’m not out in forest or field or I’m not observant enough to see those things.
Recently, lady luck smiled and I had one of those good weeks –
Sunday – We were riding our bikes when what did we see but a large bright green caterpillar crawling along. Picked it up so it wouldn’t get squashed and put it on a nearby shrub. The caterpillar was apparently a mature tobacco hornworm caterpillar searching for a spot to pupate.  Tobacco hornworms and the closely related tomato hornworm are named for the appendage on their last segment. Both caterpillars feed on tomato, tobacco, nightshade and other closely related plants. The moths which emerge from the pupae are sphinx moths that hover hummingbird-like to feed on nectar of flowers.

Monday – Walked along the river and found that the peregrine falcon is back! Today it was perched in a dead ash tree that was killed by the exotic emerald ash borer. For the last several years a pair of peregrines has spent many winter days watching from these trees ready to make a meal of the pigeons that frequent the nearby bridge.   

Tuesday – Indian-pipe is a common woodland plant in eastern woodlands – a white plant with diminutive leaves and no chlorophyll; it’s a parasite on the fungi that inhabit the roots of oak trees and are thus an indirect parasite on the trees themselves. Today in the Big Woods I glanced down and there at my feet was a red stemmed indian-pipe. Looking around, it was quickly apparent that an entire colony of this rarely encountered color variation grew in this small patch of woodland. Several of the plants even bore flowers; much later in the season than indian-pipe typically flowers.

Wednesday – In the 1990s, as part of the effort to reintroduce peregrine falcons to Pennsylvania, peregrine chicks were released atop a tall hotel in Williamsport. Ever since, one or more peregrines has spent winter nights on a high ledge on the building. This morning one of the birds was back on their old haunts on the same southeast-facing ledge. The calendar may say it’s not yet winter, but the falcons are ready.
With 1000mm lens
Enlarged on computer
Thursday – For 40 years I’ve visited Pennsylvania’s elk range to photograph the animals. Being a beautiful day, this was the day for the trip. Got a late start from home and so didn’t see many elk in the morning. Late in the day was a very different story – that’s for next week’s post.

Friday – Found a number of nodding ladies-tresses, a small native orchid that grows in abandoned fields or disturbed sites. It’s one of several species of ladies-tresses that grow in similar habitats and in this area the most common one. The flower spikes are seldom more than a foot tall, bearing gleaming white flowers amidst all the greenery. Unlike most native orchids, they’re rather common and small enough that most people don’t notice them – but they’re absolutely beautiful up close.

Saturday – The white oaks in the Big Woods are loaded with acorns this year and now those have begun to drop. White oak acorns are the least acidic of any of the acorns in northcentral Pennsylvania and so are the favorites of all the acorn-eating mammals. Today I was walking on an old road that ran through a grove of large white oak; there on the ground, with its back to the road, was a porcupine busily feeding on the acorns. Staying behind the trunk of one of the large oaks I was able to get within 15 feet of the porcupine. When it finally turned around seeking another acorn, it saw me peering around the tree and, without hesitating, hustled off. A hustling porcupine is a humorous thing to see – especially as it passed up a number of easily climbed trees and went on across the ground for several hundred feet. 

Friday, September 19, 2014

Destroying Angel

They were a few feet off the old woods road, gleaming brilliant white on the forest floor despite it being a gray, dreary, drizzly day. “They” were a scattering of mushrooms of the genus Amanita; one of several species of white Amanita that are difficult to differentiate, which even some field guides apparently confuse, all going by the common name “destroying angel”.

Destroying angel is an excellent name for these mushrooms – my favorite field guide to mushrooms notes that they are “Poisonous – deadly” and goes on to state “Do not taste this mushroom”. Another field guide cautions against even touching these mushrooms.

Over 45 years ago I listened to an account of a family that had eaten a mushroom stew later estimated to contain just one of these highly toxic mushrooms – five members of the family died. More recently, not far north of here, an elderly gentleman, who had gathered and eaten wild mushrooms throughout his life, died a prolonged and painful death after having eaten a destroying angel by mistake.

All of the literature on mushroom poisoning describes the process in similar terms: There are no symptoms for several hours (4-24) after which vomiting, diarrhea and severe abdominal pain set in; some people also become delirious and may have convulsions. These symptoms can last for several days, but then subside and the person seems to improve. However, left untreated the mushroom’s toxins proceed to cause severe damage to the person’s liver and kidneys which usually results in death in one to two weeks. 

But, there's an angelic side to these fungi also. The destroying angel, like all Amanita species, is important to the forest ecosystem because they are mycorrhizal fungi that grow in and around the fine roots of trees. In this relationship the tree provides the fungus with carbohydrates and the fungus provides the tree with water and minerals. Without mycorrhizal fungi trees grow more slowly and are not as productive and some plants, such as many of our native orchids, cannot survive. It has been estimated that 80 percent of all species of plants are dependent on mycorrhizal fungi to varying degrees.
So, some may ask, do I gather and eat wild mushrooms – NOPE. There are too many species that are toxic, many species are difficult to identify with any accuracy, and – as the old fellow found out – even experienced people can make a fatal mistake.

Thursday, September 11, 2014

Fall Webworm

Over the years many people have asked about the “tent caterpillars” that appear on hardwood trees in the late summer and fall. I’ve explained to them that these aren’t eastern tent caterpillars but are instead the webs of the fall webworm (Hyphantria cunea) that have both a very different life history and very different impact on the trees they inhabit than do tent caterpillars. 
The webs we see on hardwood trees in the fall are formed by the caterpillars of an insect that as an adult is a non-nondescript white moth having a wingspan of about three-quarters of an inch. Fall webworm caterpillars hatch from eggs that the female moth lays on the underside of leaves in early summer. Newly hatched larvae begin to spin a web to enclose the branch-tip leaves on which they feed. As the caterpillars grow they enlarge the web to cover more and more leaves and eventually the webs become large enough to attract the attention of the people who ask about the “tent caterpillars”.
The webs are quite tough and easily defeat the efforts of most birds and small mammals that would otherwise prey on the caterpillars. If the web is breached, the caterpillars immediately drop from the web. Those that fall to the ground have little chance of survival, but if they merely fall to a lower branch they have a remote chance of returning to the web or creating a new web on the host tree.

As the days shorten and the caterpillars mature they emerge from the webs, drop to the ground and pupate over winter in the leaf litter on the ground or in the soil. The adults emerge in late spring or early summer, mate, lay eggs and die.
Because fall webworm caterpillars only feed in late summer and fall, their impact on host trees is minimal. The trees have already formed the leaf and flower buds for next year and have manufactured virtually all of the sugars they need to survive the winter and grow the following spring. However, the webs sure are ugly and often hang on the trees all winter – their impact on aesthetics can be significant. 
Just as invasive exotic species are a problem in our forests, fall webworms have become invasive in Europe and Asia after their accidental introductions in Europe and Japan during the 1940s. 
So how do fall webworms differ from the eastern tent caterpillars with which they are so often confused? Tent caterpillars build their tents in the spring; fall webworms, true to their name, are active in the fall. Tent caterpillars can defoliate entire trees and even kill small trees; fall webworms seldom do either. Tent caterpillars typically use their webs to hide from predators but leave their webs to feed; fall webworms feed within their webs. Tent caterpillar webs are in the crotches of trees –
Fall webworm webs are on the tips of branches –