Bioblitz 2 - The Hatching

Earlier in the summer I helped out with identification at a bioblitz, and one of the things I was given to look at was a cluster of pupae attached to an oak leaf. It didn't take long to work out that they were a species of small parasitic wasps in the genus Eulophus, but they needed to be reared to adulthood to be identified to species. So, that's what I did...

Now empty, the ring of pupae that surround the host caterpillar (removed), giving this stage of Eulophus the name 'tombstone pupae'.

Side view of Eulophus - note the metallic green colour, much reduced wing venation and long pale legs. The body, excluding legs, wings and antennae is around 2mm long.

Note the bulges on the mesoscutum just in front of the wing bases. The line around the bottom of a bulge is called the notaulix (pl. notaulices) and is only sharp in the front half. This is diagnostic of the subfamily Eulophinae.

The antennae are inserted level with the base of the eyes, not halfway up. This is one characteristic of the genus Eulophus.

The scutellum (the upper surface between the wing bases here) is only slightly convex, not strongly bulging. This is another characteristic of Eulophus.

More characteristics - the front coxae (basal segments) are pale and the mid coxae are metallic.

These (and some other hard-to-photograph) features mean that this species is Eulophus larvarum. It is common in the UK and has two forms - the spring form (April-June) and the summer form (June-August). The summer form has a pale spot near the front of the gaster (the broad or 'main' part of the abdomen) which is seen here.

The pale/yellow spot on the gaster showing this to be the summer form of E. larvarum.

This species is a parasite of the exposed caterpillars of moths in several families in the UK. Being so tiny they are often overlooked, but careful searxching may produce specimens and they were easy to both raise (in a  ventilated lidded pot) and (to my surprise) identify, using Askew (1968) which is now available as a free download - see below.


Reference

Askew, R.R. (1968). Handbooks for the Identification of British Insects 8(2b). Hymenoptera: Chalcidoidea Section b. RES, London. [free download here]