I obviously need to slow down before clicking “publish” on my post page!
Yesterday’s post about the Painted Lady butterfly has a mis-identified inset photo. Two butterflies in the genus Vanessa resemble each other closely – V. cardui (Painted Lady) and V. virginiensis (American Lady), both of which are found in the Northeast. While the main photo was correctly identified as a Painted Lady, the inset photo is an American Lady. Details enabling you to determine which of these migrating butterflies you are seeing can be found at http://bugguide.net/node/view/236368 . (Bugguide.net is an excellent resource for anyone wanting the identity of an insect or spider. You simply submit your photo and generous entomologists provide i.d.s). Many thanks to naturalist/author Kathie Fiveash for bringing this mis-identification to my attention.
If anyone reading this blog considers fungi too boring to be of interest, they may be about to experience a change of heart. A group of fungi known as “stinkhorns” generate a lot of interest, mostly because of their appearance and their odor. These fungi vary in color, shape and size, but they all share two characteristics. All stinkhorns begin fruiting by sprouting an “egg” from which they erupt, often as quickly as overnight, and a portion of their fruiting body is covered with slime (gleba) which contains spores.
Many species of Stinkhorns have a phallic form, including Ravel’s Stinkhorn (Phallus ravenelii). Brown, foul-smelling, spore-laden slime is located at the tip of this fungus. Attracted by the odor, insects (mostly flies) land and feed on the slime. With bellies full and feet covered with spores, the flies depart, serving as efficient spore dispersers.
For the past few weeks we have been witnessing the migration of thousands of southward-bound orange butterflies, a vast majority of which are not Monarchs (although they are having a good year, too) but Painted Ladies (Vanessa cardui). Both their large numbers and the length of time that they have lingered in the Northeast this fall are unusual.
This was a good year for Painted Ladies — they migrated north earlier than usual, arriving in mid-April, possibly giving them time to have an extra generation, reproducing twice instead of once during the summer. In addition, the unusual weather we’ve been having has not been great for migrating. The butterflies have spent a lot of time fueling up on nectar while waiting for a wind out of the Northeast to assist them in their flight to the Southwest. With the prevailing wind change we’re now experiencing, it’s likely many of them will resume their migration today.
The fruits of the Hophornbeam tree (Ostrya virginiana), also known as Ironwood for its strong, hard wood, are drooping clusters of papery, bladder-like sacs each containing a nutlet. The “hop” portion of its name refers to the resemblance of these fruits to those of true hops that are used in the production of beer. Hornbeam refers to a related European tree whose wood was used to yoke oxen; therefore, its American counterpart wood was also used as a “beam” with which to yoke “horned” beasts of burden.
Winter’s coming and in the Northeast, Striped Skunks are preparing for the cold months ahead. Before they usurp the abandoned quarters of a Muskrat or Red or Gray Fox (or bunk with a willing Opossum or Raccoon), they spend a great deal of time foraging and putting on life-sustaining fat. Even though a state of torpor slows their metabolism down during the coldest months, skunks must bulk up in the fall, as they lose up to 65 percent of their body weight over the winter. Thus, they meander far and wide looking for food this time of year. In addition, this year’s young are still dispersing. For these reasons, you may have encountered the smell of skunk or the sad sight of striped roadkills in your travels lately.
Like their relatives – spiders, mites, ticks and scorpions – Daddy Longlegs, or Harvestmen, have eight legs (the second, longer, pair of legs are used as antennae). Of all the arachnids, spiders resemble Harvestmen most closely. However, there are distinct differences between the two orders. Unlike spiders, the two main body sections of Harvestmen are nearly joined and appear as one structure. Harvestmen have no spinnerets nor do they possess poison glands. They also do not have the enzymes spiders have that are capable of breaking down the insides of their prey into liquid. Harvestmen ingest small particles, breaking them down with their chelicerae, or mouthparts, which resemble miniature, toothed lobster claws. One would surmise from this photograph that the legs of flies must lack the nutrition worthy of mastication.
Getting inside the flower of Bottle Gentian or Closed Gentian (Gentiana clausa), one of our latest flowering plants, in order to collect nectar and pollen is a monumental task that few insects, other than fairly large species of bumble bees, attempt. The petals are closed so tightly it takes even bumblebees several seconds of pushing, shoving and cramming to push the petals aside and get through the miniscule opening at the top of the blossom.
Pollen is the primary bumblebee attractant, as the sugar concentration of Bottle Gentian’s nectar is fairly low. Some bumble bees take a short cut – they chew a hole to gain access to the reproductive parts of the flower. The hole is often two-thirds of the way up the blossom, directly opposite the pollen-laden anthers within the flower. Look closely at the hole in the lefthand blossom in the photograph and the adjacent, dissected blossom, and you will see that the bee’s aim was dead on. You can even detect a portion of the anther through the hole.
The Locust Borer (Megacyllene robiniae) is so-called because its host tree is Black Locust (Robinia pseudoacacia). Locust Borer larvae tunnel into a tree’s trunk and branches, weakening the tree and making it susceptible to wind breakage. In addition, these tunnels serve as a primary infection site for the wind-borne spores of the fungus Phellinus robiniae, which causes a damaging heart rot disease in Robinia species. If you see a Black Locust with many dead and broken limbs, and/or knotty swellings on the trunk, chances are great that it has been attacked by Locust Borers.
The conspicuous, brightly-colored adults appear when goldenrod is in bloom. Adults are commonly seen feeding on goldenrod pollen. Mating takes place now, in the fall, and eggs are laid in cracks, wounds and under loose bark of a Black Locust tree. The eggs hatch in about a week, the larvae bore into the inner bark of the tree and each larva makes a small hibernation cell and overwinters there. In the spring the larvae begin to bore into the woody part of the tree, enlarging their tunnels as they grow. By mid-summer they pupate and adult beetles emerge in late summer. Previously confined to the native range of Black Locust in the Northeast, Locust Borers have spread with the trees throughout the U.S. and parts of Canada.
Correction/clarification of yesterday’s post: Insects, spiders, ticks, mites, crabs, lobsters, woodlice, centipedes and millipedes are all arthropods. Of these, only crabs, lobsters and woodlice are crustaceans. Millipedes are arthropods, but are not crustaceans. (photo: Millipede. Phylum: Arthropoda; Class: Diplopoda)
Adult female Ospreys begin their fall migration in August, before their young are completely independent. After females leave, males continue to feed this year’s young and don’t reach the peak of their migration until the middle of September. Ospreys tend to migrate during the day, except when crossing over large bodies of water, which they do at night. Unfortunately, the nocturnal flights of northeastern Ospreys over the Caribbean (a 25-hour nonstop flight) on their way to their wintering grounds in South America often coincides with the hurricane season. As treacherous as this is, 80 percent of adult Ospreys survive migration, according to the National Wildlife Federation.
Arthropods are invertebrates possessing an exoskeleton, a segmented body and paired jointed legs. Crustaceans make up one group of arthropods. Insects, spiders, ticks, mites, crabs, lobsters, woodlice, centipedes and millipedes are all crustaceans. Underneath a rotting log I recently discovered a crustacean resting right next to a clump of eggs. Not wanting to disturb the creature, I hazarded a guess as to its identity from what I could see. Its form narrowed it down to either a woodlouse (also known as sow bug, pill bug and roly-poly), centipede or millipede. Most centipedes have one pair of legs per body segment, eliminating them from the field of possibilities, for the photographed crustacean has two legs per body segment, as do millipedes and woodlice.
The next clue had to do with the eggs, which I presumed were produced by the creature right next to them. Woodlice have a “marsupium,” a chamber under the thorax which is filled with water in which their (often several hundred) eggs are brooded. Millipedes, on the other hand, lay from ten to three hundred eggs at a time, and deposit them on moist soil. In some species an adult remains to guard the eggs.
I cannot categorically say that today’s subject is a millipede and its eggs, but all signs point to it. If there is a crustacean expert among Naturally Curious readers, please confirm or correct my deduced identification!
Nodding Ladies’ Tresses (Spiranthes cernua) are flowering in wetlands throughout New England. This diminutive orchid is described to perfection by Minnesotawildflowers.info as a “spiraling stalk of closely clustered, crystally translucent white flowers thrusting their twisting trumpets out at right angles to the stalk.” The downward “nodding” curve of its tubular flowers and the vague resemblance of the flower stalk to a braid may account for its common name. The flower stalk is anywhere from four to twelve inches high and the lightly fragrant delicate flowers, like those of most orchids, are resupinate. That is, they twist during their development into an upside-down position.
If you examine plants that are still flowering this late in the season (such as asters, goldenrod and late-blooming turtlehead) early in the morning when it’s still quite cool or late in the day, many of the pollinators you see will be bumblebees, not honey bees. One reason for this is that they have different temperature tolerances for flight. You rarely see a honey bee when the temperature is below 57°F as they cannot fly when it is this cool. Bumblebees, however, are capable of flight when the air temperature is as low as 50°F.
Even so, bumblebees cannot take off unless their flight muscles are above 86°F; they maintain the temperature of their thorax (where wings and wing muscles are located) between 86°F and 104°F regardless of the ambient temperature. The way in which they raise the temperature of their thorax involves uncoupling their wing muscles so that the wings themselves do not move. They then use their wing muscles to shiver and raise the temperature of their thorax until it’s sufficiently warm enough for them to fly.
At rest a bumblebee’s body temperature will fall to that of its surroundings. If it is cool out, and the bumblebee wants to take flight, you can actually see its abdomen pumping to ventilate the flight muscles. An entomologist studying this phenomenon discovered that the rate of pumping can give an indication of the temperature of the bee. It ranges from around 1 pump per second when the bee is 86°F, to 6 pumps per second when it reaches 95°F.
The lazy, hazy days of summer are dwindling, and beavers’ internal clocks are telling them it’s time to batten down the hatches and prepare for several months of life below the ice. This entails adding a significant amount of mud to the outside of their lodge. The mud freezes and creates an impenetrable barrier between them and predators such as coyotes that, thanks to ponds being frozen, will have access to beaver lodges. This mud is anchored by the addition of debarked branches and logs that have provided the beavers with meals of cambium during the summer.
A beaver can transport its own weight in material (roughly 45-60 pounds). Retrieving debarked pieces of wood in many cases involves carrying them over both land and water, using only jaws and sometimes a shoulder for support. A beaver’s short, muscular neck and its powerful lower jaw muscles make this possible. Try lifting one of the larger logs on a lodge or beaver dam sometime. Then imagine carrying it any distance in your mouth with no assistance from your hands. (This feat rivals that of a moose carrying two 25 – 30 pound antlers around for several months.) While there are recorded cases of beavers felling trees 150 feet tall and 5 feet in diameter, logs of this size are not used as building material for dams and lodges, but rather the bark and upper branches provide them with food. (Thanks to Roger and Eleanor Shepard and Sara and Warren Demont for photo op.)
The larvae of moths in the family Geometridae (the second largest family of moths in North America) are known as loopers, inchworms and spanworms. These names are derived from the looping gait of the caterpillars. They generally have only two or three pairs of prolegs (at the hind end) rather than the usual five pairs of most moth and butterfly larvae. The lack of prolegs in the middle of their body causes them to move by pulling the hind prolegs up to the true legs on the thorax in the front of their body, thereby forming a loop, and then extending the body forward.
Many Geometrid caterpillars evade predators by flinging themselves from trees and dangling by a silk thread that is attached to the tree at the other end (see photo). After the danger passes, they climb back up the silk and return to their leaf-eating.
Look closely at this photo and you will see markings in the mud as well as an abandoned spherical, muddy structure about the size of a pea. Who has been here and what have they been doing? (Enter your answer under “Comments” on today’s post at http://www.naturallycuriouswithmaryholland.wordpress.com.)
This is the time of year when Black Bears are looking for every available source of food in order to bulk up before entering hibernation. During this period of gorging (hyperphagia) Black Bears consume large quantities of fruits, berries, nuts, grasses, roots and insects.
In particular, they favor the brood (larvae and pupae) of ants, due to their relatively high content of fat and protein. Black Bears find brood by detecting the pheromones and other chemicals such as formic acid that ants use for communication and defense. Research has confirmed that Black Bears will dig up as many as 200 ant colonies a day, flipping rocks, moss and leaf litter over and tearing apart logs, stumps and snags (such as the one pictured), using their canine teeth and claws to gain access to the ants. Once they have torn apart the stump or snag, they use their long, sticky tongues to gather brood. Anthills are avoided except for when Black Bears are extremely hungry, due to the fact that bears prefer not to get a lot of soil or sand mixed in with the brood they’re eating. (Thanks to Virginia Barlow for photo op.)
The dragonfly family Aeshnidae consists of strong-flying dragonflies called darners, some of which are over three inches in length. The majority of darners reach the peak of their population in August and early September. Male Shadow Darners (Aeshna umbrosa) can be seen patrolling breeding sites a few feet over the water’s surface, searching for females and driving off competing males. Females can be observed repeatedly landing at the base of cattails, inserting their sharp-edged ovipositors and slicing open leaves, where they then deposit their eggs. If you look at the bottom third of cattails at this time of year, near the water’s surface, you will find tiny, tan, vertical slits where dragonfly egg-laying has taken place. (Photo: female Shadow Darner laying eggs)