Small World Discoveries

HYMENOPTERA > SYMPHYTA > Cephidae > Cephini

Separating Cephus pygmeus from Cephus spinipes from photos is rather difficult as both species are about the same size (5-9mm body length) and have virtually identical yellow-banded black abdomens. However, there are a few characteristics that can provide a reasonable assessment if the photos provide sufficient detail.

Although the females of both species have a generally black face except for the yellow mandible bases, the male of Cephus pygmeus is extensively yellow and the male of Cephus spinipes has a yellow spot beside each eye. For females the most reliable feature is the shape of the saw-sheath, but a good side view will be required. In Cephus pygmeus the saw-sheath is set in direct line with the oblong pale, whereas in Cephus spinipes it is noticeably angled. The antennal tips provide a further clue, but again good clear photos are needed as the difference between the two species is quite subtle. They are more swollen in Cephus pygmeus than in Cephus spinipes with the last few segments being wider than long. Finally, and possibly the best defining feature, is with regard to the colour of the hind tibia, which are mostly dark on the inner face and mostly yellow on the outer face in Cephus pygmeus, whereas in Cephus spinipes they are yellow with the apical third dark.

Both species are listed as being widespread and common, although the distribution maps indicate that Cephus spinipes is the more regularly recorded species locally. They are found in a variety of grassland habitats and around arable farmland where the larvae feed and develop inside grass stems. The adults can be seen from May to July when they can often be found on yellow flowers such as buttercups and dandelions, although they will also occasionally be seen on umbellifers.