Bumblebee Mimics

by Carl Strang

There are mimics, and there are mimics. A couple years ago at Mayslake Forest Preserve I found a syrphid fly that mimics bumblebees.

This is the narcissus bulb fly, Merodon equestris.

This is the narcissus bulb fly, Merodon equestris.

It was comparable in size to a small worker bumblebee, though none of our local bumblebee species match this color pattern, and it doesn’t really pass for more than a few seconds’ examination.

But there are others, like the one I saw yesterday:

This is more like it. It’s big, the size of a bumblebee queen, and it’s hairy, and its color pattern resembles those of a couple local species.

This is more like it. It’s big, the size of a bumblebee queen, and it’s hairy, and its color pattern resembles those of a couple local species.

This is a robber fly, a predator known to catch bees as well as other relatively large flying insect prey. There are a couple species in the East which are very similar to one another. Their larvae tunnel in rotten logs, preying even then on other larvae they encounter. After maturing, they perch in sun flecks on leaves or on more solid perches. The more common one in DuPage County appears to be Laphria thoracica.

Here’s another individual I photographed in July 2008 at Danada Forest Preserve.

Here’s another individual I photographed in July 2008 at Danada Forest Preserve.

Note the long black hairs on the top, front and sides of the head. If those were a dense solid yellow this would be a different species, Laphria grossa. I encountered those in south central Pennsylvania, and the impression was much the same. That beak probably could deliver a nasty bite if you grabbed this critter, but why would you want to? These take a longer, closer look to distinguish them from bumblebees. That beak is one giveaway. Another is the single pair of wings rather than two. Also, the perched fly frequently snaps its head to different angles, tracking possible prey. Bumblebees don’t do that. These robber flies are on my short list of niftiest local mimics.

Why the mimicry? One has to think it provides some protection from vertebrate predators. Also, these are among the largest of the robber flies, most of which are not mimics. That large size seems to slow them down, as they don’t fly nearly as fast as their smaller relatives. Perhaps the bumblebee coloration and speed leads prey to ignore them until it’s too late.

Burned Area Recoveries

by Carl Strang

The extensive areas at Mayslake Forest Preserve that received controlled burns this spring are responding vigorously, as rains and warming temperatures have supported rapid plant growth.

The fire killed the smooth sumac stems, but this is a fire-adapted species of the prairies, and new shoots are rising.

The fire killed the smooth sumac stems, but this is a fire-adapted species of the prairies, and new shoots are rising.

Though the dried herbaceous tops burned thoroughly, the wooded and wetland edges of prairies and meadows, as well as areas dense with shrubs, were less affected.

The outer, peripheral ranks of woody stems were killed, but the denser central stands survived.

The outer, peripheral ranks of woody stems were killed, but the denser central stands survived.

Of course my particular interest is in how the singing insects fared. Last week I was able to make early observations of green-striped grasshoppers, which were nymphs at the time of the burn. While it was clear that grasshoppers were few in the centers of larger burned areas, there were occasional individuals even there. Smaller areas, and edges of larger burn zones, had good numbers of grasshoppers, and so there are plenty to repopulate the prairies and meadows.

Time Lapse

by Carl Strang

Earlier this week, Sam Droege of the U.S. Geological Survey presented a new idea for crowd-sourced monitoring of environmental change over time. The idea is to set up a standardized station, or set of them, from which photos could be taken with any camera or camera phone. The shared photos then could be standardized as Sam describes, resulting in a series comparing the scene over the seasons and years. (This is not the first time one of Sam’s ideas has appeared in this blog; I featured the Cricket Crawl a while back).

The photo station idea intrigued Jon Marshall of DJ Case & Associates (developers of the Observe Your Preserve website for the Forest Preserve District of DuPage County, as well as other web-based platforms for natural resource agencies).  Jon put together a website promoting Sam’s idea, including his 3-minute descriptive video (http://monitorchange.org/). We will consider the possibilities for OYP as well.

All of this reminded me of several series of photos I took back in the 1980’s, in which I had spots identified on the ground in prairie, woodland and stream habitats, and took photos through the seasons. The slides belonged to the District, but so far I have been unsuccessful in locating them, except for five duplicates I had at home.

The old dam at Waterfall Glen in August 1984.

The old dam at Waterfall Glen in August 1984.

The same scene in December of that year.

The same scene in December of that year.

Farther downstream on Sawmill Creek in August.

Farther downstream on Sawmill Creek in August.

The same scene in November. Rocks and drift logs in the streambed are largely unchanged, in contrast with the vegetation.

The same scene in November. Rocks and drift logs in the streambed are largely unchanged, in contrast with the vegetation.

Small Mysteries

by Carl Strang

Even when distracted the mind notices, finds questions.

Some remain intractable. Why has Culver, Indiana, become turkey vulture central?

Vultures roosting at the Culver town park on a morning last week.

Vultures roosting at the Culver town park on a morning last week.

There have been times in the past decade when 30 or more vultures circled above that part of the town.

Other mysteries are more easily resolved. Back at Mayslake Forest Preserve this week, I noticed a polyphemus moth cocoon on a small tree.

The oval shape, pale color, and loose attachment to a twig are distinctive.

The oval shape, pale color, and loose attachment to a twig are distinctive.

There has been no sign of this large species on the preserve in the years I have been there. But this tree was planted just last year, and checking my notes I found that it was installed in November. Obviously the cocoon had formed in the nursery.

On another day I was startled to see a red cedar decked out in structures like Christmas tree ornaments.

These are the spore-producing structures of the cedar-apple rust, which cycles between the cedars and apples or crab trees, and can impair both host species.

These are the spore-producing structures of the cedar-apple rust, which cycles between the cedars and apples or crab trees, and can impair both host species.

It seems the cool, wet weather promoted the rust’s development on that tree.

A questioning attitude becomes reflexive when one practices inquiry and spends time out-of-doors.

Update

by Carl Strang

Circumstances have prevented me from gathering much new blog material for the past week and a half, but I hope to have more to share soon. The bird migration continues, but there’s only one photo in the hopper.

White-crowned sparrow, Mayslake Forest Preserve

White-crowned sparrow, Mayslake Forest Preserve

As for singing insects, the first few spring field crickets began singing in Marshall County, Indiana, last week, but I have yet to hear any farther north (DuPage County, Illinois).

The one significant new development came yesterday, as I was running the trails at Herrick Lake Forest Preserve. A grasshopper flew up from the trail in the large meadow of the preserve’s southeast corner. It had hind wings that were bright yellow with broad black edges. This was the first opportunity to take advantage of my recent literature research on possible new singing grasshoppers. It turns out there is only one band-winged grasshopper with that color pattern that matures so early in the season, the sulfur-winged grasshopper (Arphia sulfurea), and so I can already shift one species from the hypothetical list to the verified list for the region.

First Brood

by Carl Strang

Last week the first Canada goose brood of the season appeared on Mays’ Lake.

There were 6 fresh downy goslings.

There were 6 fresh downy goslings.

Where had they come from? There was only one nest on Mayslake Forest Preserve, but they could have followed Trinity Lake (which winds for a considerable distance west and north from the preserve) and crossed to Mays’. I checked the nest in the parking lot marsh, and sure enough, it was empty.

The nest did not appear disturbed, and the membrane of an apparently hatched egg is visible on the side of the muskrat house.

The nest did not appear disturbed, and the membrane of an apparently hatched egg is visible on the side of the muskrat house.

Unfortunately the water still is too deep to reach the nest and count hatched eggs. I tried, but that marsh is in a steep-sided bowl and I was to the tops of the hip boots within a few steps from shore. I will have to wait for the water level to drop, and hope the nest is not too deteriorated for me to get some sense of how many eggs hatched.

Singing Insect Season Opens

by Carl Strang

Saturday was the spring bird count, and for the first time in recent years I was able to participate. In the early afternoon we were standing on a grassy hill, scanning a pond for water birds in Timber Ridge Forest Preserve, when my ear caught a faint, brief buzzing sound. Then, another. By then my attention had been pulled away from birds, as it seemed I had heard northern green-striped grasshopper displays. I was unable to take the time to confirm it that day, but the next day when I returned I heard many.

Male green-striped grasshopper

Male green-striped grasshopper

Those first observations brought with them the season’s first new question. I was hearing many distinct, if low-volume crepitations, enough to declare the singing insect season open. I did not see any of the grasshoppers, however. Usually their display flights are reasonably conspicuous if you are looking for them. It was moderately windy, though. Were they able to get a normal display out of a shorter, lower flight? Were they somehow rattling their wings without flying? Perhaps later in the season, when displaying grasshoppers are more abundant, I’ll be able to find out.

Incidentally, that May 4 first date is middle-of-the-road. The earliest displays I have observed for that species in DuPage County were on April 3 of last year. The latest starting date was May 16 in 2008. This insect overwinters as a nymph, and so is able to complete its development early in the season.

The Greening of Mayslake

by Carl Strang

The once blackened, burned portions of Mayslake Forest Preserve are responding to the increased heat absorption of that dark soil surface, as well as to the release of minerals in the ashes, and plants are growing rapidly.

The savanna ridge, among the last portions to be burned, already was this green a week ago.

The savanna ridge, among the last portions to be burned, already was this green a week ago.

Among the flowers blooming in that burned area is the early buttercup.

Among the flowers blooming in that burned area is the early buttercup.

Bellworts likewise have responded with full stems and flowers.

Bellworts likewise have responded with full stems and flowers.

In the prairies, which experienced their controlled burns earlier, the green reveals that a number of taller stems still stand, their tops unscorched.

This tempers my expectation that insects whose eggs overwinter in such stems might be absent from the burned areas.

This tempers my expectation that insects whose eggs overwinter in such stems might be absent from the burned areas.

Elsewhere, other plants are in their spring glory.

Dutchman’s breeches continue to multiply in the (unburned) south savanna.

Dutchman’s breeches continue to multiply in the (unburned) south savanna.

Weeping willow flowers may not be colorful, but they offer an interesting texture to those trees in this season.

Weeping willow flowers may not be colorful, but they offer an interesting texture to those trees in this season.

The green is a welcome change in the landscape.

Bird Arrival Phenology

by Carl Strang

On Friday I shared this year’s flowering phenology through the end of April. There have not been enough first appearances of insects yet to make a comparison to previous years, but birds have been arriving at Mayslake Forest Preserve for more than a month. Most of these are species that winter in the southern U.S., and so are capable of tracking the weather conditions and adjusting their migratory jumps accordingly. Consequently the dramatic differences we see among years in plants’ first flowering dates are not reflected in the arrival dates of birds.

The first pine warbler appeared 7 days later in 2013 than in 2012.

The first pine warbler appeared 7 days later in 2013 than in 2012.

That said, the median difference between this year and last for the 31 species I could compare was 7 days later in 2013. One week, compared to nearly 5 weeks for first flowers, seems small, though it should be added that the range of arrival date differences was large, from 70 days earlier to 37 days later.

The first killdeer appeared 3 days earlier in 2013 than in 2010.

The first killdeer appeared 3 days earlier in 2013 than in 2010.

That 7 days’ difference was the largest in recent years. Median arrival dates in 2013 were 3 days later than in 2011, 2.5 days earlier than in 2010, and 5 days later than in 2009 (34 species in each case). All the ranges were large, in fact all were larger than for 2013 vs. 2012. Nevertheless, it would be hard to build a case that bird arrival dates varied much from year to year.

April Flower Phenology

by Carl Strang

We finally got some flowers in April, so it is possible to quantify how late this spring has been compared to recent years. It should be no surprise that this is the latest spring of the last 5, at least as measured by first flower dates at Mayslake Forest Preserve. It also should be no surprise that the biggest contrast is between this year and last. For the 13 species of plants I could compare, the median difference was more than a month, with 2013’s median 34 days later than that for 2012.

Bloodroot hit the median exactly, blooming 34 days later this year than last.

Bloodroot hit the median exactly, blooming 34 days later this year than last.

The smallest difference was between 2013 and 2011 (the year of the Snowmageddon blizzard). Twelve species bloomed a median 4.5 days later this year.

Common blue violets flowered 4 days later this year than in 2011.

Common blue violets flowered 4 days later this year than in 2011.

Looking back at 2010, the difference is another big one, at 17 days (11 species).

Trout lilies hit the median, 17 days later in 2013 than in 2010.

Trout lilies hit the median, 17 days later in 2013 than in 2010.

Finally we go back to 2009, my first spring at Mayslake. It seems we have alternated early and late years, as the difference again is smaller. Nine species of plants bloomed a median 5 days later in 2013 than in 2009.

The representative example in this comparison is cutleaf toothwort, right on the 5-day median difference.

The representative example in this comparison is cutleaf toothwort, right on the 5-day median difference.

If 2013 runs true to form, there will be a gradual convergence of dates as the spring and summer progress.

« Older entries

%d bloggers like this: