Seeking Robust Coneheads

by Carl Strang

Last week I began a review of singing insects I expected to find in northeast Illinois but which I haven’t yet encountered. The next species in this series is the robust conehead.

This is the range map for that katydid from the Singing Insects of North America (SINA) website. At the beginning of my study in 2006 I thought that I had found them in DuPage County, but more careful examination of photos and a found-dead specimen revealed that all so far have been round-tipped coneheads.

Like the robust conehead, the round-tipped has a relatively small cone structure at the tip of its head, but it has a larger black area. Also, it is a smaller insect.

The round-tipped conehead provides an example of how things can change over time. Here is its range map from SINA.

Note how the projected range does not quite reach DuPage County. Yet this is a common species here. Either no researcher previously has noted this or, more likely, round-tipped coneheads have expanded their range.

As mentioned last week, the next step in my search is to examine the SINA database for clues. As was the case with prairie meadow katydids, nearly all the Illinois and Indiana records for robust coneheads are from sand areas or from southern locations with which I am unfamiliar. Two exceptional records stand out, however. One is in fact from DuPage County on September 13, 1955. This observation cannot be discounted as it was made by Richard Alexander of the University of Michigan, who did a lot of pioneering research on singing insects in the Great Lakes region.

The other observation which jumped out was from my home town area of Marshall County, Indiana. That county has a lot of sandy soils, though.
I’m not sure what direction to take with this species. By all accounts its song is much louder than that of the round-tipped, so I guess in future years I need to do more nighttime cruising and listening, especially in sand areas.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: