Deer Fly - Chrysops macquarti

Chrysops macquarti/moechus

My guess would be C. macquarti. For C. moechus, the hyaline triangle usually stops abruptly right at vein M1 (see Pechuman, Horseflies and Deerflies of New York). In this specimen, the hyaline area continues beyond M1 for a distance. Most moechus I have seen do not have any hyaline area beyond M1 or only a trace of a streak. There can be some variation in macquarti as to how far the hyaline streak goes.

… JBurger, 14 August, 2007 - 2:48pm

Curious

as to the steps you used to key this specimen; I may be able to show you where you went wrong.

… A.W. Thomas, 12 August, 2007 - 8:57pm

Steps

I thought I had this one. I am using "Diptera of Illinois, Tabanidae" by Pechuman et al. as my reference.

I think couplet 18 is the only place I could be mistaken. If so, then this would be another C. pikei. The hyaline triangle seems to just reach the bifurcation and extends slightly further as a paler brown than the dark wing spots. The other spot is at couplet 22. There are two central abdominal stripes but are there lateral stripes that are counted as well? The wing pattern seems to match C. abber*ans fairly well.

I'm curious as to which species you have determined this to be.

… Brad Barnd, 13 August, 2007 - 11:31am

You may be correct

I would have stopped at couplet 17; doesn't quite look right to me to be macquarti but you have the advantage of the actual specimen.
These 2 species moechus and macquarti can be similar.
Have a look at Burton (1975) Deer Flies of Indiana, Great Lakes Entomolist Vol 8: 1-29

… A.W. Thomas, 13 August, 2007 - 3:12pm

Additional image

I'm adding a close-up of the wing to help verify which this is.

… Brad Barnd, 13 August, 2007 - 5:50pm