1912 Ennomos quercinaria (August Thorn)

Geometridae, Ennominae - Wingspan: 36-44mm.

A locally distributed species in central and southern UK, and predominantly occurring from mid to east Cornwall. One of three species which can easily be confused, so care must be exercised when determining the insect found. With this species, the outer cross-forewing line has a distinct "S" shaped kink in it at the front edge of wing. The inner cross-line is also distinctive, being strongly inward curved at the front edge of the wing as well. Darker versions of this species, like the one above, which has a smoky shading along the outer part of the forewing, can often be confused with 1914 Enommos fuscantaria (Dusky Thorn), but the cross lines are less curved in that species. It has been proposed by a well known UK Entomologist that all the "Thorns" can be identified by comparing the wing silhouettes alone, ignoring the markings altogether. It may be possible, but is easier then with set specimens, not something easy to do on live specimens.

The flight season in the UK for this species is mid August to late September, although in Cornwall this is extended to include July. Unfortunately this means that its flight season is coincident with a third species 1915 Ennomos erosaria (September Thorn), but this has not been recorded very much in Cornwall. all three "Thorns" in this group cannot be identified by date of observation alone.