Happy Halloween!

by Carl Strang

Greetings from the ghoulish Nature Nerd!

Winding Down

by Carl Strang

Autumn progresses. Wandering the landscape, we notice signs large and small of preparations for the dry, cold winter season. Most obvious are the plants, of course. At Mayslake Forest Preserve, scattered prairie dropseed clumps have become yellow fountains.

This grass is well established in a couple of the wetter prairie areas.

The river bulrushes that filled the marsh basin when it lost its water at last are senescing.

Without the bulrushes’ active transpiration, the marsh can begin to refill.

The soundscape shifts as well, insect songs becoming fewer as the calls of sparrows and finches increasingly fill the airwaves. Can the first snowfall be far behind?

Common Ground Crickets

by Carl Strang

Ground crickets are the most difficult group of singing insects to photograph. I have spent hours seeking the various species, and still do not have photos of both genders of several species for the guide I have been developing for the Chicago area. Females are easier to find. For one thing, they wander more.

Females come out into the open sometimes as they travel in search of singing males or oviposition sites.

The acrobatic individual in the above photo is a Carolina ground cricket. I also held one in a jar briefly, but when I released her she escaped before I could get a sharp photo.

Of our common three ground cricket species, the Carolina female is distinguished by her short ovipositor, shorter than the femur length.

Of course, to some degree if you have seen one ground cricket you have seen them all. Here is a female striped ground cricket.

The longer ovipositor, subtle differences in body proportions, and especially the stripes on the head separate this one from the Carolina ground cricket.

The third common species is Allard’s ground cricket. Here is an earlier photo of a female.

There is head striping here as well, but sometimes it is obscure.

Fortunately for monitoring purposes, the male songs of these three species are easily distinguished. And after all, since they are going mainly by the songs themselves, there is little if any selective pressure for them to look different. Still, I want those photos. I still need one of a male Carolina, and that is my final field research goal for this season.

Miscellaneous Encounters

by Carl Strang

It’s time to shake more photos out of the bag, as we are well into the seasonal transition. Back when the weather was hot, a male blue dasher posed at St. James Farm.

For some reason I hadn’t previously been successful in getting a good photo of a male. The forward-cocked wings are a characteristic of the genus.

A few weeks ago some odd looking mushrooms came up beneath a cluster of conifers at Mayslake.

I recognized these from my years in Pennsylvania: old man of the woods. The peculiar flaked surfaces of cap and stem are distinctive.

Recently I shared a photo of a greenstriped grasshopper nymph. At the time, I wondered whether the brown colors of males and the green colors of females might appear as early as the nymph stage. The earlier individual was brown.

Last week I ran across this green one.

So both colors at least are present in the fall. Though I cannot say for sure, the simplest explanation is that the gender-specific colors appear this early in development.

Also last week, a young house centipede explored my office walls.

I marvel at their ability to control all those long legs on a smooth vertical surface.

Of course, one advantage is that the many feet provide lots of little grippers.

One Less Red-bellied

by Carl Strang

Birds don’t molt feathers in clumps. When you find a bunch of feathers together, you can take it as a sign of predation.

This group of feathers on the mansion lawn at Mayslake Forest Preserve last week is an example.

The black and white barring all across the feathers, and their size, identify the vic as a red-bellied woodpecker. The perp? My vote goes to one of the preserve’s great horned owls. The feathers appeared plucked rather than pulled out and mangled as teeth would have done. Red-tailed hawks can take birds of this size, but woodpeckers are so nervous and alert that a nighttime hit seems more likely. A migrating Cooper’s hawk is another possibility to consider. They are predators of birds, and have a variety of sneaky tactics that might catch even a woodpecker off guard. In any case there is one less red-bellied on the preserve, but others still are around. This year’s resident pair at Mayslake raised two broods successfully, for example, so even if one of those adults was the prey, there will be a new generation ready to take its place.

In the Pink

by Carl Strang

One day last week as I walked the trail that passes the eastern parking lot at Mayslake Forest Preserve, I saw a large grasshopper posed like a female laying eggs. It wasn’t a Carolina grasshopper, and though it was the size and shape of a differential grasshopper the color was off, so I took photos that I hoped would result in an addition to the preserve species list. If it was indeed laying eggs, I didn’t want to collect it.

The subject of today’s story

When I later looked at the photos, I had to marvel. The size and shape, and the distinctive herringbone pattern on the legs, were a match for the differential grasshopper. Only one thing was off: the insect was pink instead of olive green.

A normal-colored differential grasshopper

The color would have stood out more, and I might have made the determination on the spot, if the day had not been so cloudy. I don’t know how rare pink color morphs of grasshoppers are. They turn up occasionally in the false katydids, though I have not encountered one yet. I’m glad I left it. I’ll be interested in seeing if I encounter more pink differential grasshoppers in that part of the preserve in future seasons.

Jumping Bush Cricket Range Expansion

by Carl Strang

In 1969, when Thomas Walker reviewed North American bush crickets, his paper (accessible through this link) showed the range of the jumping bush cricket, which then included the southern halves of Indiana and Ohio, and the southern third of Illinois. Since then they have expanded north, as I mentioned in my post earlier in the week which included photos of the species. The front of their northern extent now is in DuPage County. Here is where I have found them to date:

Green circles indicate locations, which in some cases represent one or two individuals, in others dozens.

The map is more representative of western DuPage than of the eastern half of the county, but I’m confident of the northernmost positions. The easternmost spread is taking place mainly along Salt Creek, and I imagine a similar expansion is happening along the Des Plaines River to the east. I know they have reached at least Batavia along the Fox River to the west. The northernmost circle in western DuPage was an isolated couple of individuals, and they were close to a plant nursery, so they might have been transported there. If so, it seems only a matter of a few years before the general front will extend that far.

Jumping bush crickets now are abundant in southern DuPage, the northern edge of their densest numbers this year roughly coinciding with route 56 (Butterfield Road).

Field Cricket Final

by Carl Strang

In September and early October I revisited driving routes I had followed in the spring, listening for fall field crickets (FFC) as I had done in May and June for spring field crickets (SFC). Then, I had noticed that SFC were limited largely to places where dense herbaceous vegetation provided shelter for overwintering nymphs. FFC spend the winter as eggs buried in the soil, and so are less vulnerable to the stresses of the cold season. Here is the current map showing the distribution of the two species in DuPage County:

Green circles represent locations with both spring field crickets and fall field crickets. Blue circles indicate spring field crickets only, yellow indicate fall field crickets only.

Clearly both species occur together in most places. Fall field crickets are more likely to occur alone than spring field crickets, in keeping with the spring observation. This year’s surveying was done in western DuPage, and next year I plan to fill in more of the eastern part of the county. If the results continue to show the pattern that appears to be emerging to date, the eastern part of the county, which became urbanized earlier and more completely than the western part, will continue to show fewer SFC because of its historical paucity of safe nymphal overwintering sites. The existence of locations with SFC but no FFC remains to be explained.

Black-horned Subtleties

by Carl Strang

Lately most of the members of the nigricornis group of tree crickets I have been catching at Mayslake Forest Preserve have proved to be prairie tree crickets. Last week I found an exception that brought out some of the subtle distinctions among these insects.

The broad black band on the underside of the abdomen narrowed this one down to being either a black-horned or a Forbes’s tree cricket.

The tips of the legs and antennae likewise were black. However, he was pale on top.

There was a diffuse darker stripe down the top of the head and pronotum, but so pale as to be ambiguous.

With this group of species it is a good idea always to look at the antenna spots. In this one the spots on the basal segment were large, fused and fairly well defined.

The spots on the second segment were very narrow, however, and well separated, as they should be in this species pair.

Another lesson I learned from this cricket was the importance of viewing angle on those second-segment spots. You need to look straight down on the inner spot with respect to its own position, rather than from the cricket’s mid-line, which gives only a slightly tangential view of the critical spot. After taking the photos I took the cricket home and he sang for me, so later the recording should allow me to determine which of the two sibling species he was.

Nemesis Bug

by Carl Strang

Today’s title is borrowed from a birding term. Someone’s “nemesis bird” is a species he or she has never observed despite repeated efforts, has become the bird at the top of that person’s wish list, and there is the sense that it is only bad luck that has prevented that first observation. My nemesis bug has been the jumping bush cricket. I first heard them singing in Culver, Indiana, on August 31, 2007. Later that same year I heard them at Channahon in northern Illinois, and in mid-October was surprised to encounter a little group of them in my own town of Warrenville. Since then they have been expanding both in range and in numbers in DuPage County, and in places are very common (I’ll share a map later).

They have proved to be very difficult to see. Their songs are loud and distinctive, but hard to locate. Last year I tried using the shotgun microphone, and learned that they are higher in the trees than they seem. The foliage reflects the sound in many directions. During this year’s driving surveys I found that jumping bush crickets are abundant at Pioneer Park, a forest preserve in south Naperville. On Thursday evening I went there to make yet another attempt to see one.

After several failed attempts, and using the headlamp in the darkness as preserve closing time approached, I moved to yet another tree and turned the light up along the trunk. There! A flake of bark had wings which it elevated slightly and vibrated in synchrony with the song I was trying to locate. I tried using the telemacro lens on the digital SLR, but it needed too slow a shutter speed. I dug out the little Olympus point-and-shoot, and extended the lens to its maximum. Now where was that cricket? OK, there, crawling up higher. I took a couple photos, but knew that from such a distance they would not be great.

Here it climbs up a vine.

I had with me a long-handled insect net, and I used it to dislodge the cricket. It fell right past my face, and landed on the leaf of a nearby Amur honeysuckle. After so many years of trying, I was nervous, and frustrated in trying to keep the headlamp on the cricket while simultaneously aiming the camera so its autofocus would function.

Fortunately she kept still and allowed me to snap away despite the headlamp and camera flash. She?

Indeed this was a female. I was sure the cricket had been singing when I first spotted it, but apparently this female was approaching the singing male when I came along. I was impressed by the cricket’s flat back, and by her size. She was a little bigger than a field cricket, so the only larger cricket in our region is the northern mole cricket.

The mottled gray-brown pattern is excellent camouflage against bark, and I now suspect they fit themselves into crevices and flakes of bark so as to be very difficult to see.

After checking to make sure the photos were usable (what did we do before digital cameras?), I got the cricket back onto the tree so she could resume her approach when the male started singing again. Then I returned through the darkness to my car, too elated to worry about what my next nemesis bug might be.

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