April 11, 2004
|WHITETAILS, CORPORALS & PONDHAWKS
A while back wildlife photographer Jerry Litton from Pelahatchie gave me the "Dragonflies through Binoculars" fieldguide. This was a wonderful gift, for it opened up a whole new world to me. Of course, I've enjoyed watching dragonflies all my life and I thought I knew about them, but when anyone begins studying something seriously for the first time, it's quickly realized just how little really was known.
This week I took the new fieldguide and my binoculars down to the Field Pond and here are the three dragonfly species I managed to identify with certainty after about an hour of watching:
You can review and order the "Dragonflies with Binoculars" fieldguide at the fifth link from the top on my "Books about Insects" page at www.backyardnature.net/amazon/insects_.htm
THE WORLD OF DRAGONFLIES
First of all, during complete metamorphosis among insects, the immature stage has a very different appearance from the adult stage. For example, butterflies undergo complete metamorphosis, and you know how different the caterpillar stage is from the winged butterfly. Dragonflies, instead of undergoing complete metamorphosis, experience simple metamorphosis, during which the immature stage is similar to the adult dragonfly, except that it is wingless, and aquatic -- it lives completely underwater. The immature aquatic stage is known as a nymph and you can view some good close-ups of one at www.mybitoftheplanet.com/wildlife/garden2003/july/cast0307.html
Over 300 North American dragonfly species occur in North America, displaying endless variations in habitat preference, mating rituals and life cycles. Some of the strangest aspects of the dragonfly's life cycle relate to its parasites. Dragonfly eggs are parasitized by very tiny wasps that fly underwater to find the eggs. Other parasitic wasps have been seen riding on certain dragonflies waiting for eggs to be laid. A certain biting gnat sucks blood from dragonfly wing veins, even while the dragonfly is flying.
Other behavior to watch for is BASKING in sunlight on cold days, WING-WHIRRING to warm the wings and keep them at peak efficiency, and OBELISKING, or raising the abdomen high to collect less sunlight and keep the body cool. Some dragonflies allow breezes to lift their wings flaglike while others glide on their widened hindwings.
By the way, low-powered binoculars that can focus up close are far better for dragonfly watching than powerful ones. Wing venation is very important in dragonfly identification, and I highlight the most important venation features to look for on my Odonata page at www.backyardnature.net/odonata.htm
Some young people still have streams in which to poke around so the other day Joe in Kingsport, Tennessee sent me a picture of "a couple of strange aquatic insect like 'worms' that my neighbor's Daughter and her friend caught in a creek behind her house. ... I am concerned if they are dangerous to them and others, so a prompt answer would be appreciated."
The picture showed cranefly larvae, and of course few things in nature are more harmless than craneflies, despite the adults looking like impossibly large mosquitoes. In North America we have nearly 1,500 cranefly species, and most of their larvae live in water or moist soil, and typically feed on decaying plant material.
You can see a cranefly larva at the bottom of my Diptera Page at www.backyardnature.net/diptera.htm
Anyone who occasionally piddles in little streams tends to run into all kinds of aquatic mysteries, many of which are larvae of the Diptera (the taxonomic order containing flies, mosquitoes, gnats, etc.). A useful, illustrated online key to Diptera larvae is at www.unb.ca/fredericton/science/biology/Invertebrate_key/Diptera/Diptera_key_NB.htm
I'm not at all sure what kind of beetles they are and what such vast numbers mean. The average person would call these 3/5-inch long (15mm) beetles "Junebugs," but their feet aren't shaped right for that and, in the world of insect identification, foot and mouth anatomy is very important. Earlier I suggested that they are some kind of "Shining Leaf-Chafer," and that's still my best bet. However, if you discount their curious foot anatomy, and add the fact that they are covered with a silvery bloom, or "pruinosity," they look just like the June Bug shown at www.biosurvey.ou.edu/okwild/misc/images/junebg.jpg
The larval stage of this whole group of beetles is a thick, short, white grub known by anyone who digs much in the soil. These grubs mainly eat plant roots, so I would say that during upcoming months a great deal of root eating will be done around here. If these beetles ate tent caterpillars, which also are super-abundant here now, things might balance out a bit.
BARN OWL PELLET
In that scanning you can see that the pellet is nearly 2 inches long and consists of slender bones enmeshed in a ball of fur and feathers. The idea behind owl pellets is that by spitting up a prey's bones, teeth, feathers and the like, the owl's stomach doesn't need to digest them. Other birds of prey, such as hawks, also produce pellets, but the owl's digestive juices are less acidic than those of other birds of prey, so spitting up pellets makes more sense.
Several hours after an owl eats, indigestible material collects in the owl's gizzard where it is compressed into a pellet the same shape as the gizzard. Once formed, the pellet moves up from the gizzard to the front end of the stomach where it remains for up to 10 hours before coming up. An owl can't eat while a fully formed pellet blocks its digestive track. When an Owl is ready for the pellet to come out, it usually closes its eyes, gets a funny luck in its face, doesn't want to fly, finally opens its beak, and the pellet simply drops out.
Owl pellet dissection is a favorite biology-class activity. In PDF format, the Carolina Biological Supply Company provides an online "Owl Pellet Bone Chart" for identifying bones in owl pellets, at www.carolina.com/manuals/manuals8/Owl_Pellet_Bone_Chart.pdf
An online "Owl Pellet Study Kit" for teachers having an owl pellet is available, also in PDF format, at www.carolina.com/manuals/manuals8/Owl_Pellet_Study_Kit_tm.pdf
You hear a bird, think you know which species it is but you're not sure, so you fire up the computer and go to the above link, and there you see a long list of bird names. Using your browser's "find" feature you locate the name on the list and click it. Most computers will then automatically load the appropriate audio file and you'll hear the bird's song. If you have a slow modem, it can take a minute or more for the file to load. You can test your computer's ability to digests the birdcalls on that page by going to the following link, for the Scarlet Tanager's call: www.mbr-pwrc.usgs.gov/id/htmwav/h6080so.wav
THIS WEEK'S MIGRATING BIRDS
The migrants are just flooding in, and you just never know when one of the more uncommon species will pop up, such as the Orange-crowned Warbler. I am very worried that I'm seeing so few thrushes. I've read that this group is especially affected by habitat destruction in tropical America, and the clearcutting of our national forests here does not help matters.
NEATNESS AS ABOMINATION
Let it be known that when it comes to neatening up the landscape for neatness' sake, what I see is habitat destruction, and there's nothing neat about it.
Above I use the word "abomination" advisedly. I am aware of the word's religious connotations, for many of us never see that word except in the Bible, where many things are classed as "abominations before the Lord." I use the word not in a religious context, but in a spiritual one, and in my opinion the destruction of life-giving habitat purely for the sake of appealing to the local community's concept of "neatness" is abomination before the spirit of the Creator.
For, when you look into the Universe and at the web of life on our little Earth, you see plainly that the Creator blossoms diversity out of nothingness, evolves sophistication out of awkwardness, and leaves strands of interdependency among all things. Whatever in spirit goes against this grand and beautiful theme of the Creator is "abomination."
The bushes and trees along that little ditch across the field provided a tiny island of habitat for a gorgeous diversity of living beings. A thriving local ecosystem of mutually dependent living things existed in an ocean of ecologically unstable monoculture grass. It was a polyphonic song sung in a desert.
And its destruction for the sake of neatening up the landscape is an abomination.
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