The Transformed Block Count

by Carl Strang

The developers who built my subdivision, in their wisdom, decided to plant mostly green ashes along the streets. That brilliance has been answered in the form of an insect, the emerald ash borer. This little invasive ash-killer has done a number on my neighborhood. A series of before-and-after shots follows, going around the block route I follow when I do my standard survey of singing insects in the warm months.

Looking north along my street in 2009.

Looking north along my street in 2009.

The same block now.

The same block now.

Turning west in 2009.

Turning west in 2009.

Same view, 2013.

Same view, 2013.

The next block, looking south in 2009.

The next block, looking south in 2009.

And now.

And now.

The final leg, facing east in 2009.

The final leg, facing east in 2009.

Hard to believe it’s the same block today, but it is.

Hard to believe it’s the same block today, but it is.

Most of the tree loss happened over a brief period of time, the second half of summer last year. Ever the opportunist, I made predictions about the response of the three singing insect species common enough for statistical comparisons between this year and last. Greater angle-wings are tree-dwelling katydids, and so I expected their counts to drop. Carolina ground crickets mainly live beneath foundation shrub plantings, so I expected no significant change. Finally, striped ground crickets prefer sun-lit lawns to shade, so I expected their numbers to increase. I was correct on two of the three predictions.

The Carolina ground cricket median count in 2013 was 7, not significantly different from 2012’s median of 5 (Mann-Whitney U-test of the ranks of all the counts led to a z statistic of 2.05, p>0.01). The median count of striped ground crickets in 2013 was 20, that in 2012 was 11. The comparison of ranks produced a statistically significant z value of 3.89 (p<0.01). I was somewhat surprised at the lack of a demonstrable difference for greater angle-wings (z = 1.00, p>0.01). The 2013 median count was 3, less than the 2012 median of 5, but the difference was not as large as one might expect. There were enough surviving trees of other species to sustain a population of the katydids, and also the removal of the nearer trees made more distant angle-wings more audible.

Mayslake Update

by Carl Strang

Today, some accumulated photos from, or at least connected to, Mayslake Forest Preserve.

The stream corridor marsh has become dry for the second year in a row, though this time it happened a couple months later.

The stream corridor marsh has become dry for the second year in a row, though this time it happened a couple months later.

Insects provided some photo ops.

This female sword-bearing conehead was the first of its kind I have seen at Mayslake in three years.

This female sword-bearing conehead was the first of its kind I have seen at Mayslake in three years.

Scissor-grinder cicadas occur in greater densities at Mayslake than in any other place I have found them to date.

Scissor-grinder cicadas occur in greater densities at Mayslake than in any other place I have found them to date.

This short-winged grasshopper appears to be a Melanoplus borealis, but I am not entirely sure.

This short-winged grasshopper appears to be a Melanoplus borealis, but I am not entirely sure.

The backdrop for the final photo is from Mayslake, but the pine tree cricket is the one Nancy Collins sent me from Wisconsin, still singing weeks later.

The cricket’s camouflage is superb.

The cricket’s camouflage is superb.

Snow fell for the first time yesterday: time for a new seasonal transition.

Color Time

by Carl Strang

Today’s post is just a celebration of some of the colors that fill the landscape this time of year. Plants that blend unobtrusively into the general background of summer green suddenly announce themselves.

At a glance one can see how the shagbark hickories, large and small, are arrayed in the Mayslake woodland.

At a glance one can see how the shagbark hickories, large and small, are arrayed in the Mayslake woodland.

The varied reds draw the eye as well. Here are three.

Virginia creeper winds up its supporting trees with brilliant starbursts.

Virginia creeper winds up its supporting trees with brilliant starbursts.

The Ohio buckeye’s leaves range from red to orange.

The Ohio buckeye’s leaves range from red to orange.

Out in the prairies, tall coreopsis offers a red that leans toward maroon.

Out in the prairies, tall coreopsis offers a red that leans toward maroon.

It’s a time that reminds us to live in the moment. We all know what’s coming.

Burn Aftermath

by Carl Strang

Mayslake Forest Preserve had much of its acreage burned for management purposes last spring, as described earlier. One result, aided by good amounts of seasonal rains, was a very lush, tall growth of prairie vegetation.

Part of one of Mayslake’s prairies on August 12.

Part of one of Mayslake’s prairies on August 12.

What impact did this have on the prairie insects, in particular the singing insects? I expected the species that lay their eggs in the tops of prairie plants would be impacted the most, but those that lay their eggs in the soil would be relatively unharmed. It was clear, though, that despite the unusual completeness of the burn, small patches of prairie here and there were missed by the fire, as were wetland and woodland edges, and there were portions of the preserve not included in the burn plan. These provided a reservoir from which affected species might spread.

My impression through the season was that the numbers of fall field crickets (a species which lays its eggs in the soil) were down from last year, but the numbers don’t bear this out. Counts on the whole in the various habitats are similar between this year and last. Likewise, the 3 species of common ground crickets are so abundant in all habitats that no quantitative comparison seems necessary.

Greenstriped grasshoppers overwinter as nymphs, and so are more vulnerable. If anything, however, their numbers seemed somewhat larger in all habitats, including burned ones.

Greenstriped grasshopper nymph

Greenstriped grasshopper nymph

Unfortunately, confusion about the species identity of meadow-dwelling tree crickets (described in a post earlier this week) prevented my gathering quantitative data last year. I did record numbers this year, though, and attended their locations through the season. It was clear that the earliest singers in this group were concentrated in unburned areas and around the edges of burned areas, where they might have hatched from eggs in the unburned adjacent habitats. As the season progressed, though, these tree crickets (mainly Forbes’s tree crickets) proved to be very mobile, and spilled into the hearts of the burned areas (where the forage no doubt was richer thanks to the burn, and where there was an advantage to escape the competition). Though numbers overall may have been down a little, there were plenty of these tree crickets to ensure a rapid population recovery.

As for meadow katydids, they all to some extent concentrate in wetlands, which were scorched in places but not thoroughly burned. There again appeared to be plenty of survivors to reproduce and fill the habitat.

Perhaps the most interesting observation relevant to this question this year was a big drop in wasps of the genus Sphex. There were a lot of these last year, crowding into the areas where swamp milkweeds were blooming. The great black wasp and great golden digger specialize in capturing katydids to feed their young, and potentially can influence populations significantly. I saw only a very few of those wasps this year. As they overwinter underground, I doubt the fire had anything to do with their absence. Whatever the cause, their departure further assured a successful reproductive season for the katydids of Mayslake.

Great golden digger

Great golden digger

The upshot of all of this is that the extensive spring burns, while they may have had some minor and spotty effects on singing insect populations (and, by extension, other invertebrates), did not devastate any populations as far as I can tell. This was somewhat surprising, but in retrospect it becomes clear that it would take an extraordinarily complete and extensive burn to have a long-term impact. Refugia within and without the burn area seem likely to carry populations through enough to recover from this disturbance.

What Happens to Solomon’s Plume Tops

by Carl Strang

Smilacina racemosa, the feathery false Solomon’s seal or feathery Solomon’s plume, is a woodland perennial herb that vanishes before we can seek it in the winter botany season. So, what becomes of its tops? This is a plant that encloses its seeds in berries, junk food for naïve first-time migrant birds (the berries are an attractive red color, but are lacking in nutritive value: White and Stiles 1985, Ecology 66:303-307). Since most of these migrants pass through in September, the tops remain upright at least that late.

A Solomon’s plume plant with berries on display

A Solomon’s plume plant with berries on display

Very quickly, though, senescence begins.

The berries are gone, and the leaves rapidly are browning.

The berries are gone, and the leaves rapidly are browning.

By late autumn the leaves will be gone, and the stalks collapsed and buried in the new load of leaf litter. This is a perennial, and the roots will grow a new top next year.

Tree Cricket Clarity

by Carl Strang

A year ago I was struggling with the identification of a group of four meadow-dwelling tree cricket species that reportedly live in northeast Illinois and northwest Indiana. They have been determined to be close relatives, and two of them had been established as sibling species by Thomas Walker of the University of Florida: the black-horned tree cricket and Forbes’s tree cricket are physically alike, and can be distinguished only by the pulse rate of their songs, which requires the analysis of sound recordings.

Forbes’s and black-horned tree crickets can be very black, as shown in this individual at Pinhook Bog in Indiana.

Forbes’s and black-horned tree crickets can be very black, as shown in this individual at Pinhook Bog in Indiana.

This is a paler representative of the species pair from the Great Marsh, also in the Indiana Dunes National Lakeshore.

This is a paler representative of the species pair from the Great Marsh, also in the Indiana Dunes National Lakeshore.

One member of this species group, the four-spotted tree cricket, is readily identified. It is pale, and has a distinctive pattern of spots on the basal segments of its antennae.

All four of the spots on the two lowest antenna segments of this four-spotted tree cricket in Fulton County, Indiana, are relatively small and well separated. The outer spot on the basal segment is nearly round.

All four of the spots on the two lowest antenna segments of this four-spotted tree cricket in Fulton County, Indiana, are relatively small and well separated. The outer spot on the basal segment is nearly round.

The final species is the prairie tree cricket. I thought I found this species last year at Mayslake Forest Preserve, again following the long-established focus on antenna spot patterns.

This individual was generally quite pale, and the antenna spots matched reference drawings for the prairie tree cricket.

This individual was generally quite pale, and the antenna spots matched reference drawings for the prairie tree cricket.

When I analyzed my sound recordings of the songs of prairie/black-horned/Forbes’s tree crickets from Mayslake and other DuPage County locations, however, they generally fell out as Forbes’s, though some recordings made at lower temperatures were somewhat ambiguous.

This confusion has been largely resolved, now, thanks to the recently completed Ph.D. thesis work of Laurel Symes. She traveled widely in her study of these species, collecting specimens and analyzing their songs and their genetic relationships. Though her focus was on female response to male songs, and the associated behavioral, ecological and evolutionary implications, the information she collected also is very helpful to my regional survey of singing insects.

Though she doesn’t say this herself in anything I have seen, it seems clear that we need to throw the time-honored focus on antenna spot patterns out the window for three of the four species, though it still holds for the four-spotted tree cricket. Laurel found a geographic separation between black-horned and Forbes’s tree crickets, with a zone of contact that may involve some hybridization. That zone is in Ohio, safely east of the Chicago region. Unless something new emerges in the future, I am following Nancy Collins in calling all our local ones Forbes’s tree crickets as a result of Laurel’s research.

As for the prairie tree cricket, it, too, seems not to be in the region, occurring well south and west of us. I will retain it on the hypothetical list, though, because Laurel’s results were less certain on this point.  In any case, as long as the temperature is warm (at least 68F), the remaining three species can be distinguished from sound recordings, so they need not be captured. All you need is the temperature, the graphs relating pulse rate to temperature, and a pulse rate count from the recording. At the standard temperature of 25C, four-spotted tree crickets have a pulse rate of 40 per second, prairie tree crickets 51 per second, and Forbes’s tree crickets 65 per second. Laurel found that selective pressures on male song and female choice keep these quite separate and narrowly defined, .

Another River Heard From

by Carl Strang

In a recent post I shared the northward progress of jumping bush crickets in DuPage County. I thought I was done with them for the season, but their numbers seemed to increase over the past couple of weeks, and I was toying with making another check. The opportunity came on Friday. After work I drove up into Lake County to pick up my race packet for a half-marathon I was running on Saturday. On the way back I drove down along the Des Plaines River in Lake and Cook Counties, windows open on a reasonably warm evening. The result was a new north location for the species, just south of the split between Milwaukee Avenue and River Road in Cook County.

Regional species map for the jumping bush cricket. Black dots indicate counties where they have been found to occur so far. The red stars indicate the farthest north locations for Kendall, DuPage and Cook Counties, the last decidedly north of the others.

Regional species map for the jumping bush cricket. Black dots indicate counties where they have been found to occur so far. The red stars indicate the farthest north locations for Kendall, DuPage and Cook Counties, the last decidedly north of the others.

The pattern seems clear. Of the four major north-south rivers that provide the best travel corridors for jumping bush crickets, they have gone farthest north along the Des Plaines River, the easternmost. Next comes Salt Creek, which flows into the Des Plaines at the Brookfield Zoo. Most of DuPage County is drained by the two branches of the DuPage River, whose crickets are yet a little farther south. My earlier check of the Fox River, just west of DuPage, turned up no jumping bush crickets, but I started my search at North Aurora. Might they be a little farther south than that? Last night I checked that possibility, and found them abundant at Kendall County’s Richard Young Forest Preserve. Upstream (north) from there I found a lot of good looking but empty habitat, and then a pocket of the crickets just north of the town of Oswego, still in Kendall County (the lowest star on the map). They are within 2 miles of the Kane County border, but apparently haven’t reached that county yet. So, the northward advance of jumping bush crickets is marked by a line extending southwest from the northernmost red star in the map. It seems likely that they have spread up into northeast Illinois from Indiana, by way of the Kankakee River and perhaps by a broader flow through towns and preserves closer to Lake Michigan.

A Little Celebration

by Carl Strang

It has been 30 years since I last published a scientific paper. My early papers were on birds and turtles, as my formal training focused on vertebrate ecology. As is clear in this blog, I have again become interested in scientific research, but now the focus is on invertebrates, specifically singing insects. The first scientific paper to result from this work just came out in The Great Lakes Entomologist. Here is the abstract:

2013 THE GREAT LAKES ENTOMOLOGIST 193

Geography and History of Periodical Cicadas (Hemiptera: Cicadidae) in DuPage County, Illinois

Carl A. Strang1

Abstract.

The spatial distribution of periodical cicada (Magicicada septendecim L. and M. cassini Fisher) emergence in 2007 did not match either historical locations of woodlands or the cicadas’ own geography in the 19th and early 20th centuries in DuPage County, Illinois. Cicadas were present in forest areas that had remained above 61 ha throughout historic times, and they were absent from areas which at some point had been reduced below 52 ha by tree removal, mainly for agriculture. Isolation of forest areas also may have contributed to local extinctions. The insects have spread into new, urban woodlands created by residential plantings. Their distribution is associated with the early growth of towns along commuter railways in the eastern part of the county (toward Chicago). A peculiar gap in the main emergence area (encompassing two adjacent cities) may be the result of the cicadas shifting their emergence four years early. An active dispersal on 9–11 June, coinciding with the peak in cicada singing in forested areas, apparently placed scattered small groups of cicadas outside the main emergence area.

1Forest Preserve District of DuPage County, P.O. Box 5000, Wheaton, IL 60189-5000.

Two species of periodical cicadas were the subject of the paper. The larger Magicicada septendecim (Linnaeus’ 17-year cicada) is on the left, M. cassini (Cassin’s 17-year cicada) on the right.

Two species of periodical cicadas were the subject of the paper. The larger Magicicada septendecim (Linnaeus’ 17-year cicada) is on the left, M. cassini (Cassin’s 17-year cicada) on the right.

Most of the content of the paper I have posted in this blog in less formal terms, for instance: https://natureinquiries.wordpress.com/2008/11/12/where-the-periodical-cicadas-were/

The study isn’t done, but a few years need to pass before I can seek more information to add to the story.

What Happens to Mayapple Tops

by Carl Strang

In recent winters I have been sharing photos of plants in that season. The featured species have been only a sample of those growing at Mayslake Forest Preserve, however, and I have begun to look at some of the ones that disappear before winter’s arrival. One example is the mayapple.

A mayapple plant in bloom

A mayapple plant in bloom

This colonial plant flowers in spring and produces fruits in late spring that are consumed by raccoons and other mammals which then disperse the seeds. In a wet year the leaves may then show signs of the mayapple rust, Puccinia podophylli.

The rust produces yellow spots on the leaves.

The rust produces yellow spots on the leaves.

By early July the leaves, especially well shaded ones, are beginning to senesce.

Leaves with browning edges

Leaves with browning edges

In early August some green leaves still may be found, but many have dried.

This stalk has one dried leaf, one largely green on August 5.

This stalk has one dried leaf, one largely green on August 5.

By early October, all the mayapple tops are reduced to dried stalks lying flat on the ground.

Parts of three mayapple stalks are in this photo. The leaf blades are gone. The stalks are yellowish brown and grooved.

Parts of three mayapple stalks are in this photo. The leaf blades are gone. The stalks are yellowish brown and grooved.

By winter, one would be hard pressed to recognize any trace of this plant in the leaf litter. The roots are ready, though, to send up new shoots when spring rolls around again.

A Stream Community

by Carl Strang

(This is a cross posting from the Observe Your Preserve website). Mussels and fishes are the larger aquatic animals living in our local streams. The rescue operation at West Branch Forest Preserve, described yesterday, provided information on the diverse species in that site. Though empty mussel shells indicated an even more diverse past, still, four common species remain.

Left, white heelsplitter; top, giant floater; bottom, fatmucket; right, plain pocketbook

Left, white heelsplitter; top, giant floater; bottom, fatmucket; right, plain pocketbook

All are filter feeders, opening the question of how they manage to coexist. If they all subsist on the same food, we might expect the best competitor to push the others out of the picture, unless a superabundance of the food prevents it from being a limiting factor. As it happens, though, there are at least two ways in which mussels separate themselves ecologically. One is by having different larval hosts. Mussels begin life as larval forms attached to the gills of fishes. Different kinds of mussels are hosted by different fish species. In fact, one reason for the loss of some mussel species from that portion of the West Branch is that their host fishes no longer live there. Another ecological separation of mussels is through substrate preference. Some mussels like silt (the giant floater is an example), some prefer sand (the white heelsplitter in this community), others heavier gravel (plain pocketbook, fatmucket). Some like stronger current, others the slower pools.

Fishes likewise prefer different portions of the stream. Pools are home for bullheads, though black bullheads are more tolerant of silt than are yellow bullheads.

Black bullhead

Black bullhead

Yellow bullhead

Yellow bullhead

Swifter current is associated with more of a gravel bottom, preferred by creek chubs and sand shiners.

Creek chub

Creek chub

Sand shiner

Sand shiner

Largemouth bass, black crappies and green sunfish hunt other animals in more open waters, while white suckers are adapted to bottom feeding.

Largemouth bass

Largemouth bass

Black crappie

Black crappie

Green sunfish

Green sunfish

White sucker

White sucker

Pumpkinseeds prefer pools with plenty of vegetation, and prefer snails as food. They, and quillbacks, are less common than generalists like the green sunfish.

Pumpkinseed

Pumpkinseed

Quillback

Quillback

Together, they sort out the different habitats within the river and form the fish community revealed during the rescue operation. For more information on these and other species, go to the individual species pages in the Observe Your Preserve website.

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