An online resource based on the award-winning nature guide

Archive for July, 2012

Spongilla Fly Cocoon

If you’ve never heard of a Spongilla Fly, you’re not alone. We don’t see its larval stage, as it lives under water, where it feeds exclusively on fresh water sponges. You can find these sponges living in the still waters of large rivers, lakes and wetlands. The beautiful silken net, as well as the small cocoon inside the net, are created by a Spongilla Fly larva after it crawls out of the water and chooses a spot on land on which to pupate (in this case on a seat cushion). The entire structure is less than ¼” in diameter.


Viceroy Butterfly

The Viceroy Butterfly closely resembles the Monarch Butterfly, but is smaller, and has a black line that runs across the veins of its back wings, which the Monarch lacks. While Viceroys don’t contain the poisonous cardiac glycosides that Monarchs do, they do contain salicylic acid due to fact that the larvae feed on willows. This acid not only causes the Viceroy to taste bad, but makes whatever eats it sick. So not only do these two butterflies look alike, but they discourage predators in the same way. This is not a coincidence. The fact that they are both toxic if eaten and are preyed upon by some of the same predators has led to their similar appearance. This phenomenon is referred to as Müllerian mimicry, and essentially it means if two insects resemble each other, they both benefit from each other’s defense mechanism — should a predator eat one insect with a certain coloration and find it inedible, it will learn to avoid catching any insects with similar coloration.


White-tailed Does Still Nursing

A doe giving birth for the first time usually has one fawn.  The following year, and until she is quite old, twins are the norm.  Triplets are fairly common, quadruplets are known, and there are at least two records of quintuplets.  Fawns nurse for eight to ten weeks before being weaned.  It’s apparent from this doe’s udder that her young are still nursing in late July.


Botfly Puparium

Congratulations on some very creative guesses!  Yesterday’s post  was a botfly puparium – a hard case made from an insect’s larval exoskeleton (skin) that covers and protects the pupa.  Most insects that go through complete metamorphosis (egg, larva, pupa, adult) don’t have this added protection for their pupal stage, but certain flies, including botflies, do.  Botflies are fairly large, hairy flies that resemble bumblebees and are internal parasites of many species of mammals, including humans. Depending on the species, the botfly deposits its eggs on or near the host animal, or on another insect, such as a mosquitoe or housefly, which carries them to their host. The eggs of some species of botflies are ingested or inhaled; those of other species hatch and the larvae bore into their host. After entering and crawling around inside of the host animal for a week or so, most species of botfly larvae settle in a spot just under the host’s skin and remain there for three to ten weeks, consuming the flesh of its host.  The lump, or “warble,” that forms just under the host’s skin where the botfly resides increases in size as the larva grows. A tiny hole chewed in the skin allows the larva to breathe, and eventually it exits through this hole.  The larva falls to the ground, where it pupates in the soil and later emerges as an adult botfly. (The two yellow bumps at one end of the puparium are spiracles, through which the pupa breathes.) The whole story of this particular puparium is that Jeannie Killam  found it in her old farmhouse’s kitchen cupboard, where it probably popped out of a visiting mouse.  (Illustration is of a human botfly.)


Mystery Photo

The subject of today’s Mystery Photo was submitted by Jeannie Killam of Barnard, Vermont.  It is approximately 1″ long, and 1/2″ in diameter.  Its identity will be revealed tomorrow — all guesses welcome!


Juvenile Green Heron

Green herons are typically solitary and secretive birds, but if you find one, you often have an extended period of time to observe it, as they often slowly stalk their prey, or pose statue-like, sometimes for minutes at a time, while waiting to strike at a fish, frog or invertebrate. Three characteristics tell you that the green heron in the photograph is a juvenile: the tufts of down that remain on its head, its streaked neck (adults have solid rufous necks) and its yellow legs (adults have orange legs).


Mating Flower Longhorn Beetles

Flower Longhorn Beetles spend their larval life boring into decaying as well as live trees, depending on the species. As adults they leave their wooden tunnels to find food (nectar and pollen), new trees to tunnel in, and to mate. I recently found several pairs of Flower Longhorn Beetles mating on Queen Anne’s Lace, and all of the males had a transparent hose-like appendage coming from the tip of their abdomen which they inserted into the females as they bred. There is actually a name for this appendage – an aedeagus – and through it sperm capsules are delivered to the female. After breeding, the males retract their aedeagi, so they are not visible. Other insects possess aedeagi in different shapes and sizes, but those of longhorn beetles are considered to be among the most impressive.