Butterflies in the family Nymphalidae are also referred to as brush-footed butterflies (their front pair of legs are much reduced, brush-like and nonfunctional). Several species of Admiral butterflies belong to this family, and one of the most common in New England is the White Admiral, also known as the Red-spotted Purple. White Admirals overwinter as caterpillars and emerge in late April to feed for several weeks on the young leaves of cherries, willows, poplars and birches, as well as other trees, before forming chrysalises and transforming into butterflies. It is relatively easy to recognize the larva of any species of Admiral butterfly, as they are our only horned bird-dropping mimics. Quite an effective way to discourage predators!
If you’ve been traveling on sunny dirt roads lately, chances are that you have seen White Admiral butterflies all over them. They are in the road to obtain salts and minerals that have leached from the soil into standing puddles and moist dirt. Because butterflies do not have chewing mouthparts as adults, they must drink their meals. While nectar is their main source of nutrition, males often supplement their diet with these minerals. The act of acquiring nutrients in this manner is referred to as “puddling.” If there’s no water around, a butterfly may regurgitate into the soil and then drink in the hope of retrieving minerals. In addition to finding butterflies on dirt roads, look for them puddling on animal scat.
The male Eastern Tiger Swallowtail butterfly (pictured) is yellow with four “tiger stripes” on each of its forewings. The female can be yellow or black, and has more blue on the hind wings than the male. Eastern Tiger Swallowtails are currently mating and laying eggs on plants which their larvae eat, which include black cherry, red maple and American hornbeam. When the caterpillars first hatch, they resemble bird droppings – an effective way of decreasing predation. As they get older, the larvae turn green and have a large head and bright eyespots.
With the warm temperatures this week, mourning cloak butterflies have been seen gliding through the leafless woods. Like eastern commas, question marks and red admirals, mourning cloaks overwinter as adults. They resemble dead leaves so much that from a distance the entire insect seems to disappear. Up close you can see the velvety texture of the wing scales, said to resemble the clothing mourners used to wear; hence, their common name. Mourning cloaks live up to ten months — an impressive life span for a butterfly. As they age, the yellow border of their wings fades to an off-white.
The striped caterpillar that is crawling along the surface of fresh snow is the larval stage of a noctuid or owlet moth (species unknown). Noctuids are dull-colored, medium-sized, nocturnal moths that are attracted to lights in the summer. They usually possess a well-developed proboscis (mouthpart) for sucking nectar. You may be familiar with the common garden pests, cutworms, which are also noctuid larvae. How this larva survives freezing temperatures I do not know, but I have seen several dozen at a time crawling around on top of the snow. Note: Jean Harrison, a fellow nature lover, just identified this larva as Noctua pronuba, a winter cutworm also known as the greater yellow underwing (moth), a recent immigrant from Europe.
Depending on the woods you walk in these days, you may be greeted by a flurry of inch-long, tan wings belonging to male Bruce Spanworm moths (Operophtera bruceata). From October to December these moths emerge , mate and lay eggs. Females cannot fly; they crawl up the trunk or branch of a tree and send out pheromones to attract winged males. After mating, the female lays eggs which initially are pale green, but become bright orange with age. The eggs hatch in the spring, and the larvae feed on a wide variety of deciduous leaves, favoring trembling aspen, willows, sugar maple and American beech. Periodic outbreaks of these caterpillars can result in heavy defoliation. In 1958 in Alberta, Canada, at the peak of a 10-year infestation, over 50,000 acres were moderately or heavily affected by Bruce Spanworm larvae.
The white-marked tussock moth caterpillar is brightly colored, with tufts of hair-like “setae.” As you might guess, it’s in the same family (Arctiidae) as the woolly bear/Isabella tiger moth. Although these caterpillars are appealing to the eye (of some people), it’s best not touch them, as their hairs break off very easily and can cause a painful reaction on your skin. There are a number of species of tussock moths, many of which, in their larval stage, have these bristles and tufts. As adult moths, most are brown or grey, and live long enough to mate, but they do not eat.
The caterpillar, or larval, stage of a butterfly or moth is the only stage in which the insect has chewing mouth parts. Hence, it is the stage during which a great deal of eating takes place. As the caterpillar eats, it grows larger, and eventually molts its skin, revealing a new, larger skin underneath the old. A cecropia caterpillar molts four times before spinning its cocoon and pupating. The cecropia caterpillar in this photograph has just molted its skin, which is attached to the plant just above the caterpillar’s head. If you look closely, you can see where the colored tubercles were. Within an hour of when this photograph was taken, the caterpillar had eaten its skin.
This 15-minute-old monarch butterfly that emerged yesterday will live for 2 to 5 weeks, long enough to mate and produce the next generation of monarchs. The generation of monarchs that emerges a month or more from now will live six to nine months, and not mate until next March or so – after flying to one of about a dozen locations in the Transvolcanic Mountains of central Mexico (a flight of up to 3,000 miles) and spending the winter. Late summer-emerging monarchs live longer than monarchs that emerge earlier in the summer because they do not immediately expend energy on breeding and the cool winter temperature in Mexico slows their metabolism, allowing them a longer life.
The larval stage of the Cecropia Moth ( Hyalophora cecropia), a giant silk moth, is a sight to behold. The yellow, blue and red knobs that adorn its 4″ pale green body are striking. Look for this caterpillar on apple, ash, box elder, cherry, lilac , birch, maple and poplar trees, whose leaves it consumes with relish. The larva spins a brown, spindle-shaped, 3” cocoon in the fall, and overwinters as a pupa inside it. In the spring, the adult Cecropia Moth , North America’s largest native moth, emerges. Brown, with a 4” to 5” wingspread, it has no mouthparts, and lives only about a week to ten days, during which time the males mate numerous times, and the females lay eggs. Unfortunately, this species of moth seems to be declining in number, in part because it suffers from parasitism by a fly that was introduced to control the Gypsy Moth.