Lesser Common Rustic Mesapamea didyma: Distribution map

Please note that the NBN Gateway map service has been terminated as of 1 April 2017.

As soon as a replacement map service is available, distribution maps will hopefully appear here again.

In the meantime, you can get some idea of distribution from the NBN Atlas website.

View the NBN Atlas Map

73.170 BF2343a
Lesser Common Rustic Mesapamea didyma

(Esper, 1788)


Wingspan 22-30 mm.

Almost identical in appearance to Common Rustic, the two species (and M. remmi, Remm's Rustic) can only be reliably separated by examination of the genitalia.

The species has been found to be fairly common and widespread throughout much of the British Isles, although information about its true distribution is still developing.

The adults fly in a single generation in July and August, and the larvae feed on various grasses, including cock's-foot (Dactylis glomerata).

The male genitalia plates depicted demonstrate the differences in the structure of the cornutus of the male aedeagus. In secalis, the cornutus is blunt ended and joined to the membrane for the whole length, whereas in didyma, it is more pointed, and joined to the membrane only for a small part of its length.
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