To celebrate the end of one year and the beginning of another, I did what I like best- to walk on the wild side in an interesting natural area, in this case Wildflower Preserve in Charlotte County, FL. The month of December in FL has been unusually cold with repeated frosts, making observations of flying insects and flowers few and far between. In such a situation I often get my dip net and explore some ponds where you can always count on uncovering something interesting on even the coldest day.
I chose a small pond that lies on the edge of a tidal creek, but is a bit peculiar in that it contains estuarine blue crabs, grass shrimp and mosquitofish, but otherwise a mainly fresh water fauna (dragonfly and damselfly nymphs, aquatic bugs and beetles, water scorpions). I have been trying to identify some of the dragonfly nymphs primarily with the help of experts that are available on a web list serve (. firstname.lastname@example.org ). With their invaluable help I have found out that the commonest dragonfly larvae present is that of the large green darner (see photo of two examples). Now a strange aspect of these two nymphs of the same species is that one is bright green and the other is the more typical brown. An odonate guru advises me that the origin and purpose of this striking green color is unknown- a rather amazing conundrum that begs for some experimental and analytical studies. He suggests that it may have something to do with the green coloration of the adults, or possibly be a type of camouflage. Such color polymorphisms in other animals are thought to be differentially useful in environments that vary from place to place or over time. Thus a species could “hedge its bets” in the evolutionary race to grow and reproduce by producing two different forms. Dragonfly nymphs are highly predaceous but rather sedentary and feed by rapidly extending an amazing mouthpart that shoots out and grasps prey (see photo).
Another tiny terror of the pond is the “toe biter” or bellostomatid water bug (see photos of top and bottom views). This is a true bug which has no biting mouth parts but instead extends a tubular proboscis out which punctures prey and delivers a toxic cocktail to paralyze and digest the hapless victim. Now as you might guess from the common name of toe biter, this small bug can provide a considerable sting if it bites you- which it will readily do if you step on one that crawls into your shoe while you are wading in water. I have experienced this several times and it is extremely painful and throbs for some time. The photo shows also that the front pair of legs is bare and seems to be designed to grasp prey, whereas the rear two pairs have hairs on them to allow for swimming. Another interesting feature of this water bug is that it breathes air (unlike the dragonfly nymph which gets oxygen from the water) and can fly from pond to pond looking for better conditions (one pond may dry up). The domestic life of this water bug is quite intriguing since the female deposits her eggs on the back of the male (“Mr. Mom”) who carries them around until they hatch.
While one may submerge your thoughts in the fascinating world of the pond, my attention was suddenly drawn to the skies as a bald eagle flew over (see photo). This bird was especially interesting since it did not have a white head and tail as do the adults. The plumage stages of bald eagles are a bit complicated but a careful study of the four stages prior to adulthood pays dividends since it allows determination of the approximate age of the bird. It is funny how such a little bit of knowledge gives a feeling of satisfaction, perhaps because so much of the lives of animals is a mystery to us. In this case the whitish belly stands in contrast with the dark breast, the feathers of the trailing edges of the wings are “sawtoothed” due to a mixture of longer juvenile and shorter replacement secondary feathers, and the tail is whitish with a dark terminal band, all indicating that this a basic two stage, or about two years old. It takes about four years to reach maturity.
So I find that whether one’s attention is drawn to bugs at the bottom of a pond, or soaring to the skies with an eagle, nature is grand and inspirational anytime of the year. I look forward to many more such jaunts in 2011.
Bill Dunson, Englewood, FL & Galax, VA