St. James Farm in April

by Carl Strang

April is a month of accelerating change, and this was evident on several levels at St. James Farm this year. Nevertheless, some observations were continuations of patterns established over the winter.

This coyote frequented the meadows along the entrance drive, and one day was joined by another, presumably its mate, distinguished by a significantly redder coat.

A second check of the great horned owl nest, in mid-April, found the adult still present. At this point it would be brooding young, which I have not yet seen.

Many plants begin to bloom in April.

Draba verna, the vernal whitlow grass, was a species I had not noticed last year.

Now that I am in my second year of observations, I can make comparisons. The median first flower date for 33 species was 3 days earlier than last year, not much different.

Spring azures were the first butterflies to appear, on April 2.

A new extension of the regional trail is being constructed through the forest this year.

The route was staked, and later cleared of trees.

I think it is important for the trail system to show off our better ecosystems. This route could have been much more damaging to the vegetation, but I would prefer that it not be so wide. I am hopeful that the new trail’s positives will outweigh its detrimental side.


Some April Insects

by Carl Strang

Insects began to appear during April’s warm spells. Inevitably I have been comparing my finds at St. James Farm Forest Preserve to my experience at Mayslake Forest Preserve, the site of my previous preserve monitoring. Some of the early insects at St. James Farm are shared with Mayslake.

The red admiral overwinters in the pupal stage.

The red admiral overwinters in the pupal stage.

Another early season butterfly is the spring azure.

Another early season butterfly is the spring azure.

Other species I never found at Mayslake.

The six-spotted tiger beetle prowls the trails at St. James Farm, as it does on many forest preserves. I was perennially surprised that I never found them at Mayslake.

The six-spotted tiger beetle prowls the trails at St. James Farm, as it does on many forest preserves. I was perennially surprised that I never found them at Mayslake.

One impressive insect I encountered at St. James Farm was entirely new to my experience. I first saw it flying, and I thought I was seeing a large bee fly or a fat bee. Then it landed.

It proved to be a beetle. The bumble bee flower beetle’s name reflects its impressive mimicry.

It proved to be a beetle. The bumble bee flower beetle’s name reflects its impressive mimicry.

This is a member of the scarab family, and it feeds from flowers, ripe fruits, and sap-exuding tree wounds.

Insect First Appearances

by Carl Strang

Yesterday I detailed the phenology of first flowering dates at Mayslake Forest Preserve. Today I want to share some equally impressive first appearances of insect species there. Most of these observations were made in the warm period in mid-March.

Before this year I never had seen a common green darner earlier than April 2, anywhere in DuPage County. This year the first migrants showed up on March 19, and tandem pairs already were laying eggs in the stream corridor marsh.

One question in the back of my mind relates to the relatively mild but snow-free winter we experienced. Some species may have benefited from the warmer winter, but others may have been set back by the lack of insulating snow. One species that may have benefited is the spring azure. I have never seen so many of those little blue butterflies as I have counted already this year.

This year’s first sighting of a spring azure came 54 days earlier than last year, 23 days earlier than in 2010, and 21 days earlier than in 2009.

So, here are the statistics. Species counts are smaller than for the plants that bloomed in March, at 5-6 species per year. First appearances ranged 16 to 80 days earlier in 2012 than in 2011, with a median of 30.5 days earlier. The range for 2012 vs. 2010 was 17 to 36 days earlier, median 23 days earlier. The range for 2012 vs. 2009 was 21 to 40 days earlier, median 28 days earlier. These medians were similar to those for first flower dates, despite the smaller numbers of species.

Tomorrow I’ll conclude March’s remarkable phenology with migrant bird arrival dates.

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.

Mayslake Lepidoptera Update

by Carl Strang

Recently I provided an update on damselflies and dragonflies that have become active at Mayslake Forest Preserve. New butterflies and moths also have been appearing. The large group of butterflies known as skippers can be tricky, but I believe I have these right: Hobomok skipper,

Hobomok skipper b

and tawny-edged skipper.

Tawny-edged skipper 2b

Both are, according to my references, common. I have found Hobomoks in other preserves early in the season. Even more common and distinctive are two more species, the least skipper

Least skipper 2b

and silver-spotted skipper, the latter never far from black locust trees.

Silver-spotted skipper b

The most recent butterfly to show itself has been the spring azure.

Spring azure 2b

Moths also are in evidence. This one, Zanclognatha cruralis, belongs to a curious group whose larvae eat dead leaves.

Zanclognatha cruralis b

The following moth I photographed on the slope between May’s Lake and the friary, not far from a large white pine.

Semiothisa bisignata cropped b

This one proved to be a tough ID. There is a large group of moth species which look very much like this one. Furthermore, many of these species show considerable variation among individuals. The yellow head and anterior thorax are unusual among them, I gather, and help to narrow down the possibilities. My tentative identification is Semiothisa bisignata, the caterpillars of which eat pine needles. In the future I may need to collect one or more of them. With some insects, photographs simply aren’t enough.

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