Moth Identification Tips
by Paul Butter
Every year there is confusion over the goup of moths in the genus Hoplodrina, commonly known as the “Rustics”. The main culprits are the Uncertain (H.alsines); the Rustic (H.blanda); Vines Rustic (H.ambigua); and the similar Mottled Rustic (Caradrina morpheus).
All are roughly the same size ( 31-38mm. wingspan) and generally brownish and mottled in varying degree. However they are not too difficult with practice, and the following tips may be useful. Vines Rustic has the longest flight period from May to October so any caught in May, September or October are more likely to be Vines Rustic.
It is the palest looking of the group, quite washed out pale greyish brown , with white hindwings.The leading edge of the forewing (the costa) lacks dots and is quite narrow. The males have ciliated antennae looking shortly bristly under a x10 handlens.
When present, the central spot (or stigma) on the forewing is minutely edged in off white. Mottled Rustic also has whitish hindwings , but murkier in appearance than Vines and with a darker edge to them. The forewings are broader from pale to dark brown but with a very markedly square central stigma appearing as a dark blodge without any fine off white edging.
The Rustic and Uncertain are the most tricky. Overall colour of the forewings is brown to greyish, even blackish, but never ochreous in the Rustic.The cross lines are more obscure. Both these species have the stigmas lined minutely in off white. The Uncertain looks a lot more banded , as the cross lines are more obvious, one always running down from the stigma to the lower edge (dorsum) of the forewing, one running a few mm in from the outer edge ( margin) and, usually, one running between the body and the stigma. Overall ochreous ground colour to forewings and a robust look favour the Uncertain. I don’t find the reference to hindwing colour in Skinners text very useful, females always have darker hindwings than males in both species.
While writing this article I found a couple of errors in the reference collection I hold myself, so don’t expect to be 100% accurate! Unfortunately all these moths occasionally have atypical forms which are bound to confuse. I would hope to get 85% of them right with a little practice.
Next Identification Tip will cover Pale Mottled Willow, Small Mottled Willow and Dark Mottled Willow.