Added Insects

by Carl Strang

It’s fun to discover new things, and at Mayslake Forest Preserve I continue to add new species of insects or plants almost daily in the summer. This week the most recent added insect was the question mark butterfly.

This species is named for the tiny silvery markings on the hind wings.

Last week this moth appeared, and I’ve seen another since.

The yellow-collared scape moth is a smaller relative of the similar looking Virginia ctenucha.

An abundant visitor of flowers in the stream corridor prairie this summer has been the great black wasp.

This solitary species digs tunnels, where it places katydids and grasshoppers for its young to eat.

A final new species remains to be identified.

One of the biggest weevils I’ve ever seen, this interesting looking insect turned up in one of the kids’ sweep nets on Take Your Kids to Work Day.

Of course, it’s also enjoyable to see familiar insects.

The wild indigo dusky wing is one of our more common skippers. I have seen them hanging around wild indigo plants at Mayslake, but their caterpillars also feed on other legumes.

Lately I’ve been seeing scattered slender spreadwings.

The pale vein at the tip of the wing, as well as the dark abdomen tip on this male, are distinguishing features.

Two bluets appeared to be large enough, and matching the correct color pattern, to identify as familiar bluets. First was a male.

The violet color seemed odd.

Later a female appeared.

She was feeding on another damselfly, which appeared to be a newly emerged forktail.

I owe thanks to Linda Padera, who accompanied me on a lunch break walk and spotted some of these insects.

The American Snout, and More

by Carl Strang

One of my favorite animal names is “American snout.” It calls forth the image of some disembodied nose floating in space. In fact it’s a reference to a butterfly with a long forward extension of its head.

This butterfly was the first of its kind I have observed at Mayslake Forest Preserve. It is more common south of us. In references you may find its species name as carinenta or bachmanii; the genus is Libytheana, and there is only one North American species.

Another preserve first was this brightly colored beetle.

The milkweed leaf beetle, like so many consumers of milkweed, has bright orange colors. These warn potential predators of the possibility of poisons the insect may have sequestered from its diet.

I saw a couple bluets that had the relatively large size and the color pattern of familiar bluets.

The males had this violet coloration, though; my guess is that they had recently emerged as adults and would be changing colors soon.

I have been seeing more Virginia ctenucha moths than usual this year, at Mayslake and elsewhere.

That’s the way it is with some insects, having occasional years with higher numbers.

Of course, a major goal of all these adult insects is to find a mate and produce eggs.

For this pair of least skippers, it’s so far, so good.

On Friday I finally saw the first Peck’s skipper of the year.

The pattern of light spots beneath the hindwing is distinctive for this species.

It’s been a good year for insects, so far.

Literature Review: Bluets

by Carl Strang

One of the papers I found most interesting in this year’s literature review had to do with damselflies (Siepielski, Adam M., Ken-Lou Hung, Eben E.B. Bein, and Mark A. McPeek. 2010. Experimental evidence for neutral community dynamics governing an insect assemblage. Ecology 91:847-857).

Familiar bluet. I can believe that this one is ecologically interchangeable with most of the others.

In particular they focused on the 34 species of North American bluets that live in lakes with fish in them (among both dragonflies and damselflies there are a few species that live only in the relatively few bodies of water in which nymphs are free of predation pressure by fishes). Using a variety of experimental, observational and comparative methods, the researchers concluded that the nymphal stages of all these species are completely interchangeable. Competition, separation into different chunks of niche space, differential avoidance of predation, none of these processes apparently separate these bluets ecologically.

Tule bluet. This species, on the other hand, in my experience sticks to the larger, more open lakes.

These bluets as a group are, however, separated from the forktails, a different group of similar-sized damselflies. Bluets are better at avoiding predators, while forktails are more efficient “at converting prey into their own biomass.” I’m not entirely sure what that means; perhaps being more predation prone, they need to be able to get by on less food and so minimize their own exposure.

Eastern forktail. The authors seem to believe that the forktails likewise are ecological equivalents. Someone needs to get the data.

If the larvae are all alike, perhaps the adults are ecologically subdivided? Siepielski et al. didn’t look into this, but they pointed out that the damselflies live in their adult stage for an average of only 4 days, compared to most of a year as nymphs. The diversification of bluet species “seem[s] to have been driven primarily by sexual selection for differentiation in reproductive structures and little else.”

Slender bluet. Another question is, why are some species much more common than others? I run into a lot more familiar bluets than slender bluets.

They suggest that similar neutral community dynamics may operate commonly among insects, given the many sibling species groups. This raised my own metaphoric antennae, as many singing insects (cicadas, crickets and katydids) belong to clusters of sibling species. Along the way, Siepielski et al. mentioned the interesting fact that dragonfly nymphs have been shown elsewhere to feed negligibly on bluet nymphs.

Orange bluet. On the whole I accept these results, but as hinted in the above captions, there may be a little more complexity to this story.

A related theoretical paper published this year (Van Doorn, G. Sander, Pim Edelaar, and Franz J. Weissing. 2009. On the origin of species by natural and sexual selection. Science 326:1704-1707) developed a model that supports the possibility of sympatric speciation where female selection of mates produces divergence. It requires the appearance of identifiers (e.g., color patches) that correlate with the different subpopulations. Females in the different environment patches then are favored to the extent that they identify and mate with the appropriate local males.

October Monitoring Run

by Carl Strang

Last weekend’s warm weather allowed me to make a late dragonfly monitoring run on the Des Plaines River at Waterfall Glen Forest Preserve. Looking back through my records, I find that in all the monitoring I have done since 2003, I never have made a formal outing in October. It was worth trying for that reason, if no other. Besides, it was a nice day to be on the river in my sea kayak. There isn’t a lot to report as far as dragonflies and damselflies go. The only dragonflies were a pair of common whitetails, the female laying some last ditch eggs. I saw a couple familiar bluets,

a few orange bluets,

a stream bluet, 3 eastern forktails and 7 American rubyspots.

The last confirmed that this species is active late in the season, supporting my sighting at Fullersburg (which at first I thought was a smoky rubyspot). I also made some singing insect observations, the best of which were jumping bush crickets singing in the early afternoon on both sides of the river. This adds to my local range for this species, which clearly has shifted north of where you will find it mapped in references. The shallow lagoon at the downstream end of my monitoring area was hosting a gathering of great egrets.

The gorilla in the room, however, was a major construction project underway on the south side of the river. A fence was being built.

With much machinery, much shouting and an impressively speedy progress (I saw no sign of this when I last was there in late August), a metal framework is being erected and filled with fine-meshed screening.

The fence is parallel to the Centennial Trail, which has been closed for this project. The fence is only 6 feet tall or so, enough to disrupt the view of trail users but not enough to be a significant barricade to wildlife, I thought. A little research on the Internet revealed the purpose of this structure. It is a fish barrier. That may seem strange, but high water levels could lift the river high enough to reach the fence. The target fish are Asian carp, a group of 4 species which have been much in the news because of concerns that they might cross from the Mississippi River drainage (which includes the Des Plaines) and the Great Lakes. The Des Plaines River is paralleled by a canal, so the fence apparently is intended to keep the carp from going between the two. Would tiny baby carp be stopped, though? I’m not enough of a fisheries biologist to judge. For more information on the fish species and other information, here is a link.

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.

Insect Phenology June

by Carl Strang

In my previous post I updated first flowering dates for Mayslake Forest Preserve in 2010. Today I’ll share first insect sighting dates for June. In the limited time I had to be out on the preserve during the month I noted only 12 new species for the year. The median difference from last year was a negligible half day earlier. These observations included the reversed haploa (15 days earlier than last year),

and Roesel’s katydid (27 days earlier).

New species for the preserve list included the familiar bluet

and the moth Scopula limboundata.

In English the last is usually called the large lace-border. It belongs to the Geometridae, or inchworm family.

Dragonflies on the Deck

by Carl Strang

I have been part of the regional dragonfly monitoring program since it began in 2003. I started counting dragonflies and damselflies at Willowbrook, Songbird Slough and Waterfall Glen Forest Preserves, in recent years focusing on the last two. Though I continued to find new species from time to time, the past couple of years I have felt the need to try something new. The major gap in my knowledge was in river species, so this year I decided to combine my loves of kayaking and dragonfly monitoring by trying out a river route. Water levels have been high, and cool weather has been suboptimal for monitoring, so I didn’t make my first excursion until last weekend. I launched my sea kayak from the forest preserve boat ramp at Des Plaines Riverway, and headed downstream into Waterfall Glen Forest Preserve.

Des Plaines monitor view b

Experienced kayakers know to tie everything to the boat. I didn’t want to risk wetting my digital voice recorder, so I tied a waterproof notebook to a deck line, tied two pencils to the notebook, wore my waterproof small camera and binoculars, and tucked everything else into my yellow deck bag.

Monitor deck 1b

I used the strongest current in the center of the river to go downstream, taking moments along the way to enjoy sights such as scattered great blue heron nests.

GB heron nest Des Plaines b

The only American rubyspot of the day made it easy by landing on my bow.

American rubyspot kayak b

Dragonflies were tougher, however. The low, seated vantage point made flying dragonflies look different, and it took a while to recognize even familiar species. They were flying fast over the center of the river, making photography impossible, and even tracking them with binoculars was very difficult. My frustration was limited by the low number of insects active in the center of the river that day. I reached a convenient turn around point after an hour, and started back following the sunlit north shore. (Current is slower near the bank, making the upstream paddling easier.) Odonata were much more abundant along the edge. Some damselflies continued to land on the boat. Here a powdered dancer and a blue-fronted dancer chose to land on the deck bag, providing a comparison shot.

Dancers kayak 1b

Other damselflies kept their distance, landing on sticks or debris. The small camera’s telephoto was adequate to get shots of the abundant blue type bluets, which proved to be familiar bluets.

Familiar bluet 5JL 1b

There also were many black type bluets, which I identified as slender bluets.

Slender bluet 5JL 1b

The most abundant dragonflies were jade clubtails, some of which liked my deck.

Jade clubtail kayak b

I was pleased to see a Cyrano darner along the way, though I was unable to get a photo. Toward the end I got a nice view of some Illinois roses.

IL roses Des Plaines b

All in all there was a nice variety of species, most of them familiar but some I missed. I look forward to a continuing learning experience as I return to this route on future weekends.

Mayslake Odonata Update

by Carl Strang

The weather has been rainy, gloomy and cool on many recent days, but when the sun appeared so did the insects. At Mayslake Forest Preserve I have been able to add new species and observations that provide a foundation for future study. Eastern forktail damselflies already have been busy laying eggs in May’s Lake.

Eastern forktails laying eggs b

Meanwhile, other damselflies are emerging. The next two photos are, I believe, of common spreadwings, a male

Common spreadwing b

and a female.

Common spreadwing female 3b

Having newly emerged, they are holding their wings together more than usual. Another spreadwing species is the slender spreadwing.

Slender spreadwing 1b

Note the contrasting pale veins of the wingtips. Another, blurry photo established that the abdomen has the characteristic length, twice that of the wings. I have seen orange bluets at both of the preserve’s lakes.

Orange bluet b

Familiar bluets also have begun to appear.

Familiar bluet b

The year’s first blue-fronted dancer was a female.

Blue-fronted dancer female b

Its abdomen is dark, including the sides of the tip, and has only a very narrow pale line down the top. Shifting now to dragonflies, I’ll start with a 12-spotted skimmer that began patrolling the stream corridor marsh in June. I expect the species to be common there. This one I photographed elsewhere in 2004.

12-spotted skimmer b

Blue dashers have been active out in the fields, and soon will be appearing at lakes and marshes.

Blue dasher female 1b

A jade clubtail has staked out a piece of the May’s Lake shore.

Jade clubtail b

Cruising farther out are the prince baskettails. Here is a UFO-ish shot of one.

Prince baskettail UFO b

And here is a common baskettail  showing the basal wingspots that are visible on some, but not all individuals.

Common baskettail spot b

A final, cautionary photo:

Eastern forktail new female b

This is not an orange bluet, but a newly emerged female eastern forktail. Note the absence of the orange at the abdomen tip plus the expanded orange area at the base of the abdomen.

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