Mayslake Lepidoptera!

by Carl Strang

I added the exclamation point in the title to fill a gap left by our punctuational butterflies. Eastern commas are usually fairly common at Mayslake Forest Preserve.

This recent example shows the source of the butterfly’s name: a contrasting silver or white mark on the underside of the wing is reminiscent of a comma.

This recent example shows the source of the butterfly’s name: a contrasting silver or white mark on the underside of the wing is reminiscent of a comma.

The week before, I thought that one of the comma’s less frequent relatives appeared.

There seems to be a separation here, a curved line plus a dot.

There seems to be a separation here, a curved line plus a dot.

Later I had to conclude that this was a question mark wannabe, a comma with a disruption in its namesake line. This was made clear by the upper wing pattern.

The pattern of black spots on the forewing is that of an eastern comma.

The pattern of black spots on the forewing is that of an eastern comma.

There have been appearances by two different moths in the same genus, and no ambiguity in this case.

This was a LeConte’s haploa on June 9. Note the gaps in the dark lines at the corners of the wings.

This was a LeConte’s haploa on June 9. Note the gaps in the dark lines at the corners of the wings.

Ten days later a reversed haploa appeared. The dark lines are connected.

Ten days later a reversed haploa appeared. The dark lines are connected.

These are tiger moths that commonly emerge this time of year, and I continue to see individuals of both species at Mayslake. The haploa caterpillars generally feed on a wide variety of plants, but I have no information on their local diet range.

Another common moth is the large lace border, one of the geometrid or inchworm moths.

Not a big moth, contrary to the name, wingspan perhaps an inch.

Not a big moth, contrary to the name, wingspan perhaps an inch.

Again, the relative abundance of this species probably is tied to its broad dietary range, which includes plants in several families.

Butterfly News

by Carl Strang

Butterflies continue to be diverse and abundant this spring, and last week brought some news to share from Mayslake Forest Preserve. Earlier I commented that question mark butterflies had a surprisingly delayed appearance, showing up in numbers on May 4 but not earlier as one would expect from overwintering individuals. I found a reference indicating that, like red admirals and some others we’ve been seeing this spring, question marks can migrate north in spring.

They looked fresh and clean in early May, like this one from a previous year, but last week I noticed that they now appear worn and tattered.

The butterfly highlight last week was an addition to the preserve species list.

This is the first gray hairstreak I have seen at Mayslake.

Also remarkable was an early-season eastern tailed-blue.

This relative of the hairstreaks usually doesn’t appear in noticeable numbers until mid-summer or so.

I made a mental note that I need to take a close look at all these little blue butterflies. Obviously I can no longer assume they are all spring azures.

Butterflies

by Carl Strang

Butterflies are the most conspicuous insects, and to the extent that they are representative, they are telling us that insects got through the winter in pretty good shape. Butterflies have been abundant and diverse this spring, both species that wintered here and ones that have migrated north. Earlier I mentioned red admirals in this context, and their congeners the American lady and painted lady butterflies have been showing up as likely migrants as well. A member of a species new to my experience appeared at Mayslake Forest Preserve last Thursday.

Obviously a fritillary, it seemed too big for a meadow fritillary and too small for other species of my acquaintance. Also, it lacked silvery spots beneath the hind wing.

My practice is to photograph doubtful cases when I can, and this time it paid off. The newcomer is a southern species known frequently to wander north, the variegated fritillary.

On Friday I saw 3 question mark and 2 mourning cloak butterflies.

One of the question marks, named for the pale silvery small markings on the underside of the hind wing.

That in itself is not all that unusual, as I have seen both species at Mayslake before. What seemed odd was, in this butterfly-rich spring, these were the first of both species I have encountered on the preserve. Both overwinter as adults, and back in March during the warm weather we experienced, I would expect to have seen them, especially with multiple sightings of both species happening now. What gives? Yet another little mystery to tuck away in memory.

Literature Review: Butterfly Range and Diet

by Carl Strang

This week’s literature review note is about butterflies. Usually we just think of butterflies as delightful, beautiful bits of nature, but those qualities also attract the interest of scientists. The scientists in this case are J. Slove and N. Janz (2011. The Relationship between Diet Breadth and Geographic Range Size in the Butterfly Subfamily Nymphalinae – A Study of Global Scale. PLoS ONE 6(1): e16057. doi:10.1371/journal.pone.0016057). The butterflies they studied are 182 species in the widespread subfamily Nymphalinae. Our local members of this subfamily include such familiar butterflies as the mourning cloak, question mark and red admiral.

Mourning cloaks pass the winter in the adult form, hibernating in a sheltering refuge.

Slove and Janz were interested in seeing if there is a relationship between the diet breadth and the geographic range of these butterflies. They wanted to test a prediction that species which eat more kinds of plants have larger ranges. The diet of interest is not that of the adult butterfly, but rather of the caterpillar.

Mourning cloak caterpillars eat the leaves of trees in several families, so they would be regarded as having a wide diet breadth.

It turns out that the prediction holds. The point is that there are a lot of different kinds of plant-eating insects. Some have broad diets, others have narrow ones. How did this diversity come about? The possibility being considered is that some insects have large geographic ranges, in part because by eating a number of kinds of plants they can spread over the collective ranges of those plants. Over the course of time, circumstances such as climate change (interposing a glacier or desert, for instance), geological events (raising a mountain range or sea, for example) and chance isolations (a few representatives driven to a remote island by a storm, perhaps) divide a wide-ranging species into separate groups that no longer can interbreed. Each group may then specialize on the reduced menu of plants available to them, and over time can evolve into separate species. This is called the oscillation hypothesis, because over a long period of time it predicts an alternation between wide diets and narrow diets within a genetic line.

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.

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