The Other Side of Range Extensions

by Carl Strang

The aspect of singing insect studies that has been of greatest general interest, and about which I have presented talks most frequently, is range extensions. Most of the several examples uncovered so far have been northward extensions of species ranges, and it is easy to jump to the conclusion that this is a product of global climate change.

The first species I found well north of where it previously had been known was the broad-winged tree cricket.

The first species I found well north of where it previously had been known was the broad-winged tree cricket.

If climate is the primary influence in these range extensions, we would expect the southern boundary of a species’ range to shift north as well. However, sticking with the example of the broad-winged tree cricket, its range has expanded south as well as north. I know that only because Tom Walker, the authority responsible for the Singing Insects of North America website, informed me that he has found them spreading down into parts of Florida where they had not been before.

Documenting an expansion northward is easier than demonstrating a disappearance in the south portion of a species’ range. It is easier to prove a positive than a negative. Also, when one has limited time and financial resources, it is not possible to travel south and conduct the necessary regional surveys. So, what to do?

The best idea I have had so far is to identify species whose southern range boundaries occur in my region, and make a point of documenting their presence and estimating their abundance from year to year. There are four best candidates.

The dog day cicada Tibicen canicularis has the northernmost southern range boundary. It is mapped down into the very northern edges of Indiana and Illinois, but I have found it a little farther south, at Braidwood Dunes in Will County, Illinois, and in southern Marshall County, Indiana. My notes suggest that its numbers may vary considerably from year to year in the latter location.

Dog day cicada

Dog day cicada

The broad-winged bush katydid Scudderia pistillata is mapped a little farther south, but I have found it infrequent in DuPage County, Illinois, and its season of activity seems to conclude sooner here than it does farther north. So far my surveys have turned it up in Lake County, Illinois, as well, but not farther south.

Broad-winged bush katydid

Broad-winged bush katydid

The striped ground cricket and sword-bearing conehead are abundant in the region. Their southern range boundaries are mapped about half a state south, but that is the same distance as a number of the northern range shifts I have observed. If entire ranges are shifting, one would expect them to be more scarce.

Sword-bearing conehead

Sword-bearing conehead

This is yet another topic of interest I am keeping in mind while surveying the region’s singing insect species.

Dispersal Ability

by Carl Strang

In order for us to understand insects well enough to know which ones need the most attention in conservation, there are some pieces of information we need: how abundant they are, how broad or narrow their habitat needs, their reproductive potential, and their dispersal ability. The first two items are readily obtained in the course of a regional survey such as I am conducting for singing insects in northeast Illinois and counties in neighboring states. Reproductive potential has been studied to some extent and can be found in the literature for some species. Dispersal ability is a critical point that is not well studied as far as I can tell, and so it is good to take advantage of observations that reveal which species spread easily, and which ones do not.

Over the past two weeks I spent much time in the St. Joseph Hospital in Mishawaka, Indiana, where the medical professionals saved my mother’s life.

The hospital was built 3-4 years ago, and is surrounded by extensive areas planted mainly in native prairie plants.

The hospital was built 3-4 years ago, and is surrounded by extensive areas planted mainly in native prairie plants.

Occasionally I took walks along the paths, or made observations while arriving or departing. The species present in the plantings can be regarded as ones with high dispersal ability. These included field crickets (I cannot be sure which, as this was the cusp between the spring and fall field cricket seasons), striped and Allard’s ground crickets, Carolina grasshoppers, Roesel’s katydids, and a sword-bearing conehead. All of these are regionally abundant, and fairly broad in their habitat (dry to mesic mixes of grasses and forbs). Three have good flying ability (in the case of Roesel’s, there are long-winged individuals as well as medium and short-winged ones). Field crickets and the ground crickets can take advantage of their regional abundance and tendency to hop and walk over land. One limitation here is that I was only able to make observations over a brief portion of the season.

If I had to point to the weediest singing insect in our region, I’d have to say it’s the striped ground cricket, which is the quickest to appear in a new site.

June Insect Phenology

by Carl Strang

As I described in the previous post, plant phenology this year has been marching along in its usual pattern of between-year convergence of first flower dates. The results for insects in June were less consistent, and therefore more interesting. First appearance dates of 17 insect species in June were a median 11 days later in 2013 than in 2012. This is not surprising, given last year’s early season. There was some convergence, as that difference was 33 days in May.

The first sighting of Bombus auricomus at Mayslake Forest Preserve was on June 14 this year.

The first sighting of Bombus auricomus at Mayslake Forest Preserve was on June 14 this year.

No such convergence appeared in the comparisons of 2013 with 2011 and 2010, where the June median was 11 days later this year than in 2011 (19 species), and 9 days later than in 2010 (19 species). The differences in May were 10 days in each case, so no change. The median showed no difference (0 days) between June first appearances in 2013 and 2009 (19 species); in May that difference was 5 days.

The first monarch butterfly arrived from the South on June 13 (and yes, this is a photo from an earlier year).

The first monarch butterfly arrived from the South on June 13 (and yes, this is a photo from an earlier year).

We had some warm weather, but on the whole this spring was cool and often rainy. I think that weather pattern probably accounts for 2013’s continued lateness through June, and the relative lack of convergence to date.

June Flowering Phenology

by Carl Strang

Already by this point in the season it is clear that first flowering dates are converging, the differences among years becoming smaller by the month. Nevertheless, this year’s median June difference from last year (among 69 species) was 14 days, a full 2 weeks later (the May difference was 24 days).

Staghorn sumac first opened flowers on June 14 at Mayslake Forest Preserve this year.

Staghorn sumac first opened flowers on June 14 at Mayslake Forest Preserve this year.

Musk thistle, less desirable in the landscape but beautiful nevertheless, first bloomed on the same day.

Musk thistle, less desirable in the landscape but beautiful nevertheless, first bloomed on the same day.

Last year was an anomaly, a hot dry spring following a mild winter. When this year’s first flower dates are compared to those for the previous 3 years, the differences are much less. Flowers appeared a median 1.5 days earlier than in 2011 (62 species), 5 days later than in 2010 (45 species), and 4 days earlier than in 2009 (50 species).

Okanagana balli in DuPage County

by Carl Strang

Sunday was hot, sunny, and nearly calm, good conditions for seeking short grass prairie cicadas in DuPage County. The University of Illinois at Chicago research group had not sought them in my county, but I knew of two remnant prairies that were good possibilities. I started at the West Chicago Prairie Forest Preserve. The first short trail loop from the parking lot goes through a high quality prairie portion, and as it happened that was all I needed.

Here is one of 9 Okanagana I heard or saw at West Chicago Prairie.

Here is one of 9 Okanagana I heard or saw at West Chicago Prairie.

Having established them in one location I went on to the Belmont Prairie, a state Nature Preserve managed by the Downers Grove Park District.

Belmont Prairie is much smaller than West Chicago Prairie, but its high quality core is at least as large as the Woodworth Prairie where there is a stable population of Okanagana.

Belmont Prairie is much smaller than West Chicago Prairie, but its high quality core is at least as large as the Woodworth Prairie where there is a stable population of Okanagana.

Some clouds had come in, but the sun appeared frequently, and I heard a few cicada songs.

This one was singing from a gray dogwood adjacent to one of the trails.

This one was singing from a gray dogwood adjacent to one of the trails.

That may be as much as I will be able to do with this species this year, as the end of its brief activity period is approaching.

Short Grass Prairie Cicada

by Carl Strang

I celebrated the 4th of July by making a long-anticipated trip to the Woodworth Prairie in northern Cook County. This has been identified by a research group at the University of Illinois Chicago, led by Dennis Nyberg, as a primary location for Okanagana balli, the short grass prairie cicada. They indicate the peak activity of the cicadas as mid-June to mid-July. I missed them last year, finding the UIC information a little too late. I got there at 11 a.m., the indicated start of the cicadas’ peak daytime activity period. My first impression was how small this prairie remnant is.

Woodworth Prairie is only 5 acres, and surrounded on all sides by residential and commercial properties. It is owned by UIC.

Woodworth Prairie is only 5 acres, and surrounded on all sides by residential and commercial properties. It is owned by UIC.

A continuous buzzing sound was audible, but it was high-pitched and faint. Separate rapid pulses could be discerned, so I knew I wasn’t hearing Roesel’s katydids, but the singers were difficult to locate. I walked the trails a bit, impressed by the little prairie’s botanical diversity and minimal presence of non-prairie plants, but decided to see if I could get some guidance in the prairie’s interpretive center.

Michelle Budniak was the guide on duty.

Michelle Budniak was the guide on duty.

Michelle was new to the site, and didn’t know much about the cicadas, but she was willing to lend me her young ears (if a paraphrase of Britain’s bard is acceptable in an Independence Day story). We were able to get close to a singing cicada, and within 20 feet or so I was able to hear him clearly. We were in the final stages of a stalk when there was a movement, and one of the little cicadas flew in and landed on a nearby plant.

This is a tiny cicada, about the same size as a Cassin’s 17-year cicada at an inch or an inch and a quarter long.

This is a tiny cicada, about the same size as a Cassin’s 17-year cicada at an inch or an inch and a quarter long.

What ensued was a capsule lesson in singing insect biology. The arriving cicada was a female, drawn by the male’s song. She flew even closer to us and he appeared (he had been on the far side of a compass plant leaf, which blocked our view of him).

The two cicadas traded wing-flick signals, indicating their acceptance of one another as mates.

The two cicadas traded wing-flick signals, indicating their acceptance of one another as mates.

Soon they were connected, and remained so for about 10 minutes.

Soon they were connected, and remained so for about 10 minutes.

I was able to get satisfactory photos and sound recordings of the cicadas, benefiting from Michelle’s observation that they were most active when the sun was not blocked by clouds. I felt ready to recognize their song should I encounter them elsewhere. Though the song is faint to my ears, the SongFinder renders it quite loud, and with the reduced pitch it is recognizable as a cicada song, a continuous rapid pulsing resembling that of a swamp cicada or lyric cicada.

European Wool Carder Bee

by Carl Strang

Sunday was the Forest Preserve District of DuPage County’s Pollination Day event. Planned and assembled by Nikki Dahlin, the event drew a good crowd, families enjoying games, activities and group and individual learning opportunities that exposed them to the world of pollination. I helped set it up, and led walks to seek insect pollinators in action. It was a windy day, and most of that action was taking place in the gardens surrounding Mayslake Hall. One insect species in particular caught our attention.

The kids immediately concluded that these were bees. I wasn’t so sure.

The kids immediately concluded that these were bees. I wasn’t so sure.

They were hovering, zipping around, acting for all the world like flower flies, family Syrphidae. They even appeared to have just two wings when they landed. Eventually, though, one of them fanned his wings and showed that there were four. Bees, indeed!

They proved to belong to the species Anthidium manicatum, the European wool carder bee. The females are leaf cutters, but also gather plant leaf hairs to use as nest liners. The males are considerably larger than females, and aggressively defend territories around clusters of flowers from other species as well as their own. A European species first noted in North America in 1963, they now occur across the continent. They visit mainly gardens with Old World flowers, consuming pollen and incidentally pollinating flowers.

Slow Day

by Carl Strang

Saturday was cool with intervals of rain, so there wasn’t much to be done with singing insects. I checked out Springbrook Prairie in the morning, and Tri-County (JPP) State Park in the evening, hoping for spring trigs, but no luck there.

Walking the trails at Tri-County, I found a dark grasshopper.

It was on the trail, had the colors of a green-striped grasshopper, but was large, perhaps an inch and a quarter long.

It was on the trail, had the colors of a green-striped grasshopper, but was large, perhaps an inch and a quarter long.

It was unable to perform a sustained flight. Somehow I missed the fact that it had lost one or both hind legs. I am not fully confident of my grasshopper anatomy, but this individual appears to be a female, which would account for the size. It is, then, an unusual brown female of the species (typically, females are green, males brown). And that was it for Saturday’s research production.

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