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Insects Active in Winter

Winter Stoneflies Still Emerging

4-2-14 stonefly 123It seems early, especially with feet of snow still on the ground, to be seeing insects flying around, but some have actually been present all winter. An order of insects (Plecoptera) known as stoneflies spends its youth (one to four years) living in streams before emerging as winged adults. Some of these species, referred to as winter stoneflies, emerge from January through April, providing food for early-returning, insect-eating migrants, such as Eastern Phoebes, Tree Swallows and Red-winged Blackbirds. Stoneflies only live a few weeks, during which time they mate and lay eggs. Some do not feed, and others consume plant material. Because stoneflies are intolerant of polluted water, if you see one it’s a good indication that the water quality of the stream that it came from is excellent.

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Backswimmers Active Under Ice

11-18-13  backswimmers under ice 061Backswimmers are insects classified as “true bugs” and belong to the order Hemiptera. Most Hemipterans are land dwelling, such as stink bugs and assassin bugs, but there are a few, such as water striders, water boatmen and backswimmers, that are aquatic. In the fall, when most insect hatches have ceased, backswimmers come into their own. While some hibernate at the bottom of ponds in winter, others remain active, sculling through the water with their oar-like hind legs that are covered with fine hairs, preying on all forms of life up to the size of a small fish. Thanks to bubbles of oxygen that they obtain from pockets of air just under the ice and carry around with them like mini aqua lungs, backswimmers can continue to stay below the surface of the water for several minutes. Like most aquatic insects, backswimmers supercool their bodies (produce antifreeze compounds called cryprotectants that allow their body fluid to go down to 26 to 19 degrees F. without freezing). Right now, when there’s a thin layer of ice on most ponds and no snow covering it, you might want to peer through the ice at the edge of the pond to see if you can locate any of these cold-hardy creatures. Just be sure you don’t fall in, as I did two seconds after this photograph was taken. My undying gratitude for those of you who have donated to Naturally Curious, as your support enabled me to replace both camera and lens!

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Adult Stoneflies Emerging

7-2-13 stonefly adult 058Stoneflies spend their larval stage on the bottom of streams, in amongst the stones for which they’re named. Some species of larval stoneflies feed on decomposing organic matter, others are predators. As adults, very few stonefly species feed due to their short life span. Those that do feed on algae and lichens, nectar, or pollen. After shedding their skin 10 to 22 times (depending on the species), the larvae crawl out of the water, split their skin a final time and emerge as winged adults. Most emerge in the spring or early summer, though some species mature in the fall, and even in winter. Most larvae spend 10 to 11 months under water, and only 1 to 4 weeks as terrestrial adults. The adults spend their days hiding on the branches or leaves of streamside vegetation, and crawl around at night. They usually only fly to disperse to a new habitat, which is surprising, given the size of their wings.


Goldenrod Ball Gall Fly Larva

3-22-13 goldenrod ball gall fly larva IMG_6182The round “ball” that is often present on the stem of goldenrod plants contains the overwintering larva of a fly (Eurosta solidaginis). A year ago an adult female fly laid an egg in the stem of the goldenrod plant. The egg hatched and the larva proceeded to eat the interior of the stem. As it did so, the larva excreted chemicals which caused the plant to grow abnormally, creating a ball-shaped “gall.” If you were to open a goldenrod ball gall today, you would probably find an overwintering larva (if a downy woodpecker or parasitic wasp hadn’t gotten there before you). Within the next few weeks the larva will pupate, and as early as April the adult fly will emerge from the gall, having crawled out the passageway that it chewed last fall. An inflatable “balloon” on its forehead allows the fly to burst through the remaining outermost layer of tissue at the end of the passageway. The adult fly lives about two weeks, just long enough to mate and begin the process all over again.


Mating Flies

3-18-13 mating flies IMG_6645 (2)It’s hard to believe that flies are not only active but mating now, given the snow and low temperatures that Vermont is still experiencing, but these two flies were perched atop coyote scat doing just that. They are in the Heleomyzidae family, whose members are often found in dark or cold places, and are most likely to be encountered in the spring or late fall. There are species associated with caves, mammal burrows, carrion and birds’ nests, in addition to scat.


Winter Stoneflies Emerging and Mating

3-4-13 stonefly IMG_5015Stoneflies spend the larval stage of their life in streams, but as adults they are terrestrial. When the larvae mature, they leave the streams they grew up in, split their larval skins and emerge as winged adults, ready to mate. Most species mature in warmer months, but there are two families, referred to as winter stoneflies, that emerge at this time of year, perhaps because of the scarcity of predators. You can often find these cold-hardy stoneflies crawling around on top of the snow near streams.


A Great Christmas Present!

If you’re looking for a present for someone that will be used year round, year after year, Naturally Curious may just fit the bill.  A relative, a friend, your child’s school teacher – it’s the gift that keeps on giving to both young and old!

One reader wrote, “This is a unique book as far as I know. I have several naturalists’ books covering Vermont and the Northeast, and have seen nothing of this breadth, covered to this depth. So much interesting information about birds, amphibians, mammals, insects, plants. This would be useful to those in the mid-Atlantic, New York, and even wider geographic regions. The author gives a month-by-month look at what’s going on in the natural world, and so much of the information would simply be moved forward or back a month in other regions, but would still be relevant because of the wide overlap of species. Very readable. Couldn’t put it down. I consider myself pretty knowledgeable about the natural world, but there was much that was new to me in this book. I would have loved to have this to use as a text when I was teaching. Suitable for a wide range of ages.”

In a recent email to me a parent wrote, “Naturally Curious is our five year old’s unqualified f-a-v-o-r-I-t-e  book. He spends hours regularly returning to it to study it’s vivid pictures and have us read to him about all the different creatures. It is a ‘must have’ for any family with children living in New England…or for anyone that simply shares a love of the outdoors.”

I am a firm believer in fostering a love of nature in young children – the younger the better — but I admit that when I wrote Naturally Curious, I was writing it with adults in mind. It delights me no end to know that children don’t even need a grown-up middleman to enjoy it!


Bruce Spanworm Moths Flying

If you’ve walked in New England woods recently, chances are great that you’ve noticed light tan moths with a one-inch wing span flitting about — an odd sight for this late in the year. These are male Bruce Spanworm Moths (Operophtera bruceata), also called Winter Moths, as the adults are active from October to December. They belong to the Geometer family of moths, the second largest family of moths in North America, which includes many agricultural and forest pests. The males are seeking wingless, and therefore flightless, females to mate with. Eggs are laid in the fall, hatch in the spring, the larvae pupate in the summer, and emerge as adult moths in the fall. Bruce Spanworm larvae periodically defoliate hardwood trees, preferring the buds and leaves of sugar maple, American beech and trembling aspen trees.


Insects in Winter

What happens to insects this time of year?  A few remain active, such as snow fleas, and some, like monarch butterflies, migrate, but the vast majority of insects overwinter in New England.  The insects that stay here are susceptible to freezing due to the fact that they cannot control the temperature of their body.  Some insects, such as woolly bear caterpillars, can tolerate having ice form in their tissues, but most insects go into a state known as diapause.  When the days start getting shorter, these insects reduce the water content of their body, as water freezes at a high temperature compared to other liquids, and replace it with glycerol, which acts like antifreeze, protecting them from freezing.  (Due to technical problems which hopefully will be resolved soon, I am unable to include a photograph with this post.  My sincere apologies.)


Honeybee Hives

Rarely do you see or hear about honeybees attempting to construct a hive outdoors that isn’t inside a hollow “bee tree” or in a rock crevice.  Occasionally they do attempt it, but as the empty cells in this exposed comb attest to, honeybees aren’t likely to make it through a Vermont winter without some shelter for their hive, even a winter as mild as the one we just experienced.


Snow Flies

It always comes as a surprise to see tiny creatures moving nimbly over the surface of the snow.  However, there are quite a few insects and spiders that do, thanks to the glycerol that they produce in their body fluids that keep them from freezing.  The Snow Fly (Chionea sp.) is wingless, probably because at sub-freezing temperatures, it would be very hard to generate enough energy for maintaining flight muscles.  They (along with other flies, mosquitoes and gnats) do have two vestigial wings called halteres, the little knobs on the fly’s thorax.  They inform true flies about the rotation of their body during flight, and are thought to act as sensory organs for the flightless Snow Flies.  Throughout most of the year Snow Flies can be found in leaf litter, but come winter the adults emerge, mate and lay up to 200 eggs.  The lack of predators such as dragonflies and most insect-eating birds makes winter a relatively safe time for Snow Flies to be out and about.  Their life span is about two months, during which time they drink by pressing their proboscis against the snow, but don’t eat.   (Snow Fly in photograph is a female, measuring less than ½”.)

 


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