Dragonfly Notes

by Carl Strang

Today I want to share some observations of dragonflies from last week. It was, as you know, stinking hot all week, reaching 100F on Thursday and Friday. In the late morning on Friday, with the temperature in the mid-90’s, I was taking an early lunchtime walk along the May’s Lake shore. I noticed that the black saddlebags all were flying in an unusual position.

All had this peculiar abdomen dip, which they held as they flew.

It was reminiscent of the obelisk posture, shown by a perched dragonfly pointing its abdomen up at the sun. This is thought to reduce overheating in the insect’s body. I wonder if the saddlebags, in that extreme heat, likewise were reducing the size of their abdomens’ exposure profile. They were among the largest dragonflies I saw that day, which further might increase their danger of overheating.

Earlier in the week I was walking through one of Mayslake Forest Preserve’s prairies when I saw a common pondhawk carrying a relatively large prey to a perch.

It had caught a smaller dragonfly, a female eastern amberwing.

Female and immature male pondhawks have such perfect grass-green camouflage that they are practically invisible when perched in prairies and meadows. They are sit-and-wait predators, zooming out to catch passing insects. This predation on another dragonfly is not so rare. I once saw one catch a calico pennant, a dragonfly larger than the amberwing.

Mayslake Update

by Carl Strang

Today I want to share some miscellaneous notes on what has been happening at Mayslake Forest Preserve. Most of these are reflective of the season. For instance, thousands of migrating dragonflies have been passing through in recent weeks. Most of these have been green darners, with some black saddlebags and wandering gliders. I also saw the preserve’s first swamp darners (but was frustrated in my attempt to photograph them as they patrolled the stream). Some of the green darners paused to mate and lay eggs.

Birds also have been migrating. A good mix of warblers and others, including this scarlet tanager, have been refueling on Mayslake’s insects and berries.

Some insects appear late in the season. An example is this adult locust borer, the preserve’s first record of the species.

Of course, our year-round residents continued their activities, with signs of preparation for winter. For example, I have been seeing more skunk tracks than usual, in one case accompanied by scats.

The season’s progress makes this a time of daily change, and time spent outdoors inevitably brings its rewards.

Saddlebags

by Carl Strang

I have been seeing unusual numbers of red-bodied saddlebags dragonflies this season. They aren’t exactly swarming, but it seems that every time I go around Mayslake Forest Preserve I see at least one. Saddlebags are a group of relatively large dragonflies in the skimmer family that have patches of color on the bases of their hindwings. Our common one in northeast Illinois is the black saddlebags.

Our least common species, which is a rare wanderer from the Gulf Coast, is the striped saddlebags.

It has a red abdomen, but note the characteristic white stripes on the thorax. I photographed this one in 2004 close to the Des Plaines River. It must have followed the Mississippi River from Texas, then the Illinois River to the Des Plaines to reach northeastern Illinois.

There are two other red-bodied saddlebags we are more likely to see. Not long ago I shared a photo of one at Mayslake, repeated here.

I am not familiar enough with the two species to identify them in flight. This may be a Carolina saddlebags or a red saddlebags. Last week, however, I got a rare opportunity to examine one close up.

This insect was fluttering in the Willowbrook Wildlife Center parking lot, apparently having been caught on the front of a car. At first I was going to call it a red saddlebags, because of the dull red color and the small black spots on the tip of the abdomen. However, the ovipositor on the underside of that tip reveals that this individual is a female. Females can be dull colored relative to males. According to my references the colored area of the wing is much larger in the Carolina saddlebags, matching the extent on this individual. The deciding factor, however, is the forehead.

The forehead is the triangular area between the large squarish tan face and the eyes. There is a dark purple line across the lower half of the forehead on this dragonfly, which in the female marks it as a Carolina saddlebags.

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