Chalky Wave (7158)

Scopula purata

Family Geometridae, subfamily Sterrhirnae

Photograph copyright by Tony Leukering

10 June 2012

Steelmantown bog

CMMP block D12

Distribution map

Like Horned Spanworm, Chalky Wave is a geometer, readily discerned as such by its spread-wing posture at rest. Though it may not appear so in this picture due to the strong focus on the moth, when I found it, I initially passed it off as a bird dropping. Fortunately, I looked closer! Even a quick glance at the distribution map will provide the information that the species seems to have a strong coastal-plain affinity. Whether this apparent affinity is real or just an artifact of poor sampling -- and the few number of locations might well indicate that -- is unknown. However, given the few records, even on the heavily human-populated East Coast, I suspect that the species is probably tied to some rarish host-plant species. Given that we apparently do not know what that host plant is and that none of the usual picture sources (Bug Guide, BAMONA, and MPG) have a photograph of the caterpillar, I think that my hunch may be correct.

Another feature of this picture is that, upon finding the beast, I rummaged through Beadle and Leckie and found a depiction that looked very similar. Yet, when I posted this picture on my Flickr site, another Flickr member suggested that it was not, in fact, Large Lace-border, the species in the field guide that I had picked as the ID of this moth. I found that, going through MPG, that person was correct and it was confirmed as correct on Bug Guide. So, yet another lesson learned. Again. (Is that really "learned," then?) Just because something in the moth field guide looks quite close, check all of the resources available, because the field guide(s) cannot possibly cover all of the possibilities and all of the variations within those possibilities when dealing with moths.