Old Mystery Solved

by Carl Strang

Today’s story brings back a number of points I have tried to make over the years. For instance, there’s the idea that when one is engaged in natural history inquiries, there always are innumerable unanswered questions cooking away in memory. Sooner or later, opportunities come to answer some of them. Back in 2006, on the first day of the Roger Raccoon Club camp at Willowbrook Forest Preserve, some of the kids noticed an impressive insect.

It was perched on one of the outer roof beams of the picnic shelter.

Everyone checked it out.

It was a fly, most of an inch long. I suspect the underlying question in most kids’ minds was, will it sting or bite me?

The appropriate response to model in this situation is not fear, but interest and curiosity. Fortunately my response was interest and curiosity, so no problem. I took photos (making a record from different angles, yet another point I like to make), and noted aloud that it did not have a biting fly’s beak.

I thought it might be one of the bee flies, and that there might be some connection between it and the hole in the wood just above it, from which something appeared to be protruding.

My limited references at the time were no help. I kept the photos, and there they sat until last week. In the most recent edition of American Entomologist magazine there was a series of articles on citizen science, and one of them described an on-line publication, the Canadian Journal of Arthropod Identification. I checked it out, and found that one of its papers was a clearly illustrated key to Canadian bee flies. I remembered my photos from 2006, and was pleased to find that it didn’t take long to identify the fly. It was Xenox tigrinus, and when I plugged that name into the BugGuide website, I learned that this fly is a parasite of carpenter bees. So, not only did I get the identification, but I made the connection to the hole in the wood. The protruding object apparently was the fly’s pupal case.

Here are the reference and the link: Kits, Joel H., Stephen A. Marshall, and Neal L. Evenhuis. 2008. The Bee Flies (Diptera: Bombyliidae) of Ontario, with a Key to the Species of Eastern Canada. Canadian Journal of Arthropod Identification. doi: 10.3752/cjai.2008.06 (or: http://www.biology.ualberta.ca/bsc/ejournal/kme_06/kme_06.html ).

Early Insects

by Carl Strang

This spring, plants have been flowering a couple weeks ahead of last year, and some of the insects are making early appearances as well. This spring azure butterfly was out by April 12 at Mayslake Forest Preserve.

The earliest dragonfly of the year always is the migratory common green darner, the first of which showed up on April 5. That’s one of my earliest observation dates for the species. Last week I found a few other odonates at the stream corridor marsh, including this pair of common spreadwings in wheel position.

There also were both eastern and fragile forktails, the latter a new preserve record. Another new insect for the Mayslake list was this skipper, which I believe is a Juvenal’s duskywing.

A colony of eastern tent caterpillars is well under way north of the off-leash dog area.

To the right of the nest you can see the egg mass from which the caterpillars emerged.

Though flowers are blooming earlier, pollinators have not been caught napping. Here a carpenter bee visits cut-leaved toothwort flowers.

At first I thought it might be a Bombus impatiens worker, but the queens of that bumblebee species still seem to be searching for nest sites. At most they are beginning to tend their first set of larvae. The lack of yellow on the relatively hairless abdomen of this individual rules out all bumblebees.

Finally, I can declare the singing insect season to be open. The first greenstriped grasshoppers were displaying at Mayslake on April 20. In my 5 years’ experience with singing insects this is the earliest crepitation I have heard from that species, by 8 days.

Early Insects

by Carl Strang

Large insects are beginning to appear at Mayslake Forest Preserve. For some weeks I have been seeing mourning cloaks, which overwintered as adults.

Mourning Cloak b

The above photo I took at Fullersburg last year. Another butterfly that overwinters as an adult is the eastern comma. This one at Mayslake apparently had a close call, probably with a bird. Note the missing section from the left hind wing.

Eastern comma b

There have been some orange sulfurs, which overwintered in the pupal stage.

Orange sulfur b

Their close relatives the cabbage whites have been common all over the preserve. Earlier  I celebrated the arrival of the first common green darner dragonflies, migrants from the South. The first locally emerging dragonfly I saw was this male common whitetail at Mayslake last week.

Common whitetail immature male b

He is recognizable to species and gender by his wing pattern, but he has newly emerged and so still has the immature coloration on his abdomen. The first mature Mayslake damselflies were eastern forktails.

Eastern forktail male b

The above photo of a mature male is from a few years ago, I believe at Songbird Slough, but this is our most common and widely distributed damselfly.

I have not had good luck photographing bumblebee queens this spring. Bombus impatiens has been common, and I saw one Bombus fervidus near the friary on May 22, at the same honeysuckle bush that hosted two of these:

Carpenter bee 2b

This is the large carpenter bee Xylocopa virginica.

The first monarch butterfly arrived at Mayslake this week.

Monarch 2009 1b

This individual is too clean to have made the trip all the way to Mexico and back. It is an offspring of those that wintered down there, made part of the journey back north, and laid their eggs on milkweed plants they found in the southwestern U.S. I shake my head in amazement at the instincts that guide these insects, with their pinhead brains, through journeys last made by their great grandparents.

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