Jackpot!

by Carl Strang

I have continued to search for small meadow katydids at Mayslake Forest Preserve, and in my most recent effort I hit the jackpot. I visited some low, sedge-dominated wet areas (though with dry soil at this time of the year) at the east edge of the preserve.

In all other habitats I found around one katydid in every 2-3 sweep-net samples. Here each 25-sweep sample had several. In four samples I caught a total of 18 meadow katydids. By far the majority (13) were slender meadow katydids. There also were short-winged meadow katydids, among them this male.

At first I thought this nymph might be a straight-lanced meadow katydid, but a close look at the claspers at the end of his abdomen said otherwise.

The blunt, blade-like, slightly bent shape is that of a short-winged. I did find a couple female straight-lanced, including this one with an impressively long ovipositor.

I also picked up a couple tree crickets, both of which I think are, yet again, black-horned or Forbes’s. One was a relatively pale nymph.

The other was a more typical adult.

This experience, along with suggestions from the literature, point me toward wet, sedge dominated areas for further explorations.

Reclamation

by Carl Strang

On Friday a few of us paid a visit to the Oak Meadows Forest Preserve’s country club building.

Looks good from this side, doesn’t it? The building is about to be demolished. Here is why.

This was a sad sight, the ballroom where the Forest Preserve District staff used to have an annual holiday party. A few weeks after the last of those events, in February 2009, lightning struck and much of the building burned. We were there looking for furniture we could use, but I also was interested in the speed with which life had begun to invade.

Moss was spreading over much of the former ballroom floor.

Furthermore, reproduction had occurred: this fireweed plant (appropriately named, given the scene) was releasing seeds. Except for such propagules, these organisms will be wiped away as demolition proceeds, but is it disturbing or reassuring that life always is in the wings looking to reclaim the land occupied by our works?

Back to the Drawing Board

by Carl Strang

In a recent post I featured fork-tailed bush katydids.

I mentioned that the notes of their song are very similar to those of a secondary song produced by the greater angle-winged katydid.

Greater angle-wings are common in woods and neighborhoods across the eastern and southwestern U.S. Their typical, very distinctive song is a series of rapid, regular ticks, perhaps 4-8/second and lasting a few seconds. Sometimes, though, they produce loud, single “zik” calls that are very similar to those of the fork-tailed. I mentioned that in the New York Cricket Crawl the instructions say that the greater angle-wing produces this note no more than once every minute, while the fork-tailed emits it several times per minute. I was not comfortable with this distinction, and in fact it is contradicted by another reference, Elliott and Hershberger’s Songs of Insects. They say that this note can be produced every few seconds by either species, but in the fork-tailed it is limited to series of 1 to 3 at a time.

Over the past few nights I have heard a pattern produced by three different greater angle-wings in two widely separated locations that better fits the Elliott-Hershberger description. The pattern consisted of the loud raspy notes at 2-3-second intervals over a period of 30 seconds to 2 minutes, a brief pause, the ticking sequence, pause, and then a resumption of the loud raspy notes. In each case the sounds all were coming from the same point high in a tree.

I can no longer go with the Cricket Crawl description, which may in fact be valid for that local area. For now I will stick with the Elliott-Hershberger suggestion, and hope that at some point I can learn to distinguish the sound quality of the notes produced by these two species.

Kayak at Last

by Carl Strang

I was beginning to wonder if I would get the opportunity to put a paddle in the water this year, but circumstances allowed me to run my dragonfly monitoring route on the Des Plaines River at Waterfall Glen Forest Preserve this past weekend. Of course, in the context of this blog the monitoring is the main thing, but on a personal level it’s been hard to go almost a year without paddling. My sea kayak has taken me through north Georgian Bay.

It’s given me sights like this, Devil’s Island in the Apostles of Lake Superior.

On Sunday afternoon the sea kayak Water Strider was my vehicle yet again. I found no new species, but was interested to find that the counts for various species fell between the values for last year’s August 2 and September 3 counts, despite other measures of phenology generally placing this year earlier than last. Common whitetail and eastern amberwing dragonflies were closer to the August 2 count, though both exceeded any of last year’s counts for those species. Powdered dancers and stream bluets fell between the counts of last year’s dates. Familiar bluets were closer to the September 3 count. Many, like those in the following photo, were ovipositing.

Skimming bluets showed a significant increase, with 10 counted on this trip against 1 for the entire 2009 season. In contrast, jade clubtails were missing this time, and orange bluets were few. I wonder if their seasons are done for this year.

Straight-lanced Meadow Katydid

by Carl Strang

Yesterday I described sweep sampling. The day after I tried out the technique in the stream corridor prairie, I shifted to Mayslake’s savannas. The first sample, taken in the tall herbaceous vegetation at the edge of the north savanna, produced this female meadow katydid.

The critical feature, as I understand it, is the length of the ovipositor, the sword-like extension at the tip of the abdomen. On this individual the ovipositor is longer than the femur, and so I conclude that it is a straight-lanced meadow katydid. This was the first species on the list of those I had not yet found, as it is said to be very common. The song is a faint, high-pitched, continuous trill, which fates it to blend with all the other insect songs even with the aid of the SongFinder. The short-winged and slender meadow katydid songs are easier to pick out because the trills are relatively short and preceded by ticks. The spaces, starts and stops allow those songs to stand out. Other features that may distinguish it from those other two small meadow katydids are the short wings (compared to the slender meadow katydid’s very long ones) and the green abdomen tip (that of the short-winged meadow katydid is yellow).

Among the other insects that turned up in the savanna sweep samples was this little caterpillar, which may be an early instar of the polyphemus moth.

I will continue to seek out the more obscure singing insects.

Sweep Sampling

by Carl Strang

There are two groups of singing insect species about which my knowledge is most lacking. First there are the ground crickets, which are audible but have songs that often are similar, and they are difficult to catch for the purpose of identification. And then there are the small meadow katydids, whose songs are so high pitched that I can no longer hear them, or are so soft that they are overpowered by the many other louder species around them. Thanks to the SongFinder I have found two of these, the short-winged meadow katydid and the slender meadow katydid. Last week I employed another technique in this search: the sweep net.

A sweep net is like a butterfly net, but the bag is made of a heavy close-woven fabric that withstands being swept back and forth through vegetation. I started my search in the stream corridor prairie at Mayslake Forest Preserve. I tried taking 25-sweep samples in various parts of that prairie. The first interesting insect I caught was this one.

I released this bird-dropping-mimic butterfly caterpillar after photographing it. I thought it looked familiar, but never had seen one live. Later I found that it was a viceroy butterfly larva, which is almost identical to that of the red-spotted purple. The two species are very closely related, being in the same genus, but selection has pushed adult color development in two entirely different directions. The sweep sampling session added one new species to the preserve list.

This is a citrine forktail. Several fell into the net, but they are so well camouflaged and so still on their perches that I had not noticed any before. The singing insects I caught belonged to familiar species. Here is a female short-winged meadow katydid.

I also caught a tree cricket. This was a more typical example of the black-horned/Forbes’s species pair than the individual I described in a post a few days ago.

Though pale on the back, it was dark beneath the abdomen, and the antennal spotting was unambiguous.

Those spots are large, dark, and smudged together.

Mud on the Damselfly, Egg on My Face

by Carl Strang

During the past month, the long awaited Damselflies of Chicagoland by Marla Garrison was published on line. I finally checked it out last week, and was blown away by how excellent it is. If you have an interest in this insect group you really need to become acquainted with this work. As I skimmed through it I noticed that the smoky rubyspot was listed among the species that have not yet been confirmed in the area. Back in 2008 I had photographed a damselfly at Fullersburg Woods that I identified as a smoky rubyspot, and included it in one of this blog’s first posts.

I forwarded the photos to Marla, and she tactfully reminded me that some damselflies, including the rubyspots, submerge themselves completely when laying eggs. Salt Creek is muddy. This in fact is an American rubyspot with a thin coating of mud. Marla noted that the mud had worn off in a few spots, including the ovipositor, which is pale instead of the all black color that would be shown by a smoky rubyspot. I am disappointed, of course, that I need to remove this species from the list of those with which I have some experience, but I have gained knowledge from the episode.

Fork-tailed Bush Katydid

by Carl Strang

Earlier this week I encountered a katydid on the concrete drive near the friary at Mayslake Forest Preserve.

Its wing and head shape placed it among the bush katydids. It was too small for a Texas bush katydid, and its wings were too narrow for a broad-winged. To identify it I had to catch it and photograph the tip of its abdomen. I was rewarded with a surprisingly sharp nip on the finger which, though it grabbed my attention, didn’t even break the skin.

The distinctive shape of the gray structure gives this insect its common name. I had photographed one a few years earlier, at Fullersburg Woods.

Though references say these katydids frequent bushes and herbaceous growth as well as trees, in my limited experience this is a tree-dwelling species in northeast Illinois. Its song is a bit of a challenge, being typically a single quick lisping rasp of the wings that, to my ear, is not much different from the alternate song of the greater angle-winged katydid. The only suggestion I have seen that promises a solution to this difficulty is in the instructions for the New York Cricket Crawl. They suggest that this sound is produced only once every few minutes by the greater angle-wing, while the fork-tailed calls several times a minute. I suppose until I have reason to believe otherwise, or can learn to distinguish the two, I shall have to follow this demarcation.

Scissor-Grinder

by Carl Strang

The Tibicen or annual cicadas are a late summer phenomenon whose loud songs characterize the August days. Occasionally you may find a shed nymphal shell or a dead adult on the ground, but generally they sing out of sight, high in the trees. Last week at Mayslake Forest Preserve I had a rare opportunity to watch one in action.

This was a scissor-grinder cicada, singing only 10 feet up in a crab. The bright white underside perhaps explains its species name, pruinosa.

The cicada was walking around in the branches, singing at frequent intervals. In this photo it apparently is feeding, as its beak is extended.

The cicada was alert and watchful. As I moved within 15 feet for a closer photo the insect abruptly stopped in mid-song and was gone.

A few days later I found a dead one on the walkway near the chapel.

I have not seen a concentration of this species anywhere to match that at Mayslake. In the evening their EE-SHER-EE-SHER-EE-SHER-EE songs can drown out everything else. (Before I learned their conventional common name I used to call them lazy-dying-battery cicadas, as their song reminded me of a car engine whose battery was on its way out. This was to contrast them with the angry-dying-battery cicada, Tibicen auletes, aka northern dusk-singing cicada, whose song also is slow but has an edge to it).

Mayslake Miscellany

by Carl Strang

A highlight at Mayslake Forest Preserve this year was a successful red-tailed hawk nest. The single fledgling stuck around the mansion grounds and prairie area for several weeks, frequently making its presence known with high-pitched calls (“feed me!”) or perch choice on favored high points.

The bird has been absent from that area in recent days. We wish it well.

One day in mid-August there was much activity by black-capped chickadees and blue-gray gnatcatchers among the goldenrods and Queen Anne’s lace.

Their small size and acrobatic ability allows them to exploit a temporary abundance of insects in such places. I suspect the gnatcatchers were migrants. Already the season is turning.

The red-colored saddlebags dragonflies have vanished, after being a daily presence for the early part of the season.

Like this male, I suspect that all or most were Carolina saddlebags. I wasn’t the only observer in northeast Illinois seeing more of these than usual. That’s the way it is with insects. A species has an outbreak year, for reasons we often don’t understand, then usually drops back to its typical low level the following year.

« Older entries

%d bloggers like this: