8
The Essex Naturalist
Only caddis flies (Trichoptera) remain to cause confusion, as they also hold
their closed wings like a tent over the body. They can be recognised by their
quite different venation, stouter antennae (in most, but not all, species) and by
the presence (in British species) of hairs arising from the wing membrane (all
hairs on the wings of lacewings arise from the veins). In fact, freshly emerged
British caddis are usually so densely hairy that it is necessary to depilate them in
order to see venation. However, specimens from light traps, for example, may
often be so rubbed that the wing membranes may appear hairless, so some
caution is needed by inexperienced entomologists. Recognition problems should
only be really likely to arise with the wax flies (Coniopterygidae). These are
rather unusual lacewings in appearance as they are all very small and in the field
resemble whitefly, aphids or psocids.
One of the problems that has beset the study of lacewings and their allies in
Britain over the last thirty years has been the lack of adequate, English language
identification keys. The last such work was published as far back as 1959 in the
Royal Entomological Society's Handbooks for the Identification of British Insects
series (Fraser, 1959) and is inevitably now out of date. In addition, a number of
problems arise from the use of that work; most notable is the reversal of the
tarsal claw characters in the couplet which separates Chrysopa abbreviata from C.
phyllochroma - the latter now known to comprise two species, not one - and the
printing errors which make the key to females of the scorpion flies Panorpa
species totally unworkable. There are other errors too. Fortunately, this key is
now out of print, and so unless you already have a copy it is best forgotten about
altogether! The best keys by far that are currently available are those in Die
Neuropteren Europas, written in the German language by Horst and Ulrike
Aspock with Herbert Holzel in 1980 (Aspock et al, 1980). These include all of
the European species (though not the Mecoptera) and include genitalia
drawings of most and wing photographs of all. They are particularly useful in
terms of being aware of potential new species colonising Britain, as appears to be
the case with Semidalis pseudouncinata and Hemerobius fenestratus, and of species
which have been residents for longer periods but whose presence may still
remain undetected, as was the case with Coniopteryx esbenpeterseni (vide Plant &
Hynd, 1991) and C. lentiae (vide Hynd, 1989). However, there are two major
drawbacks to the use of this two-volume work: first, it is in German, a language
which, sadly, few British people can understand, and secondly it costs in the
region of £240.
A number of interesting papers have appeared in the literature since 1980, a
few in Britain but rather more in the rest of Europe, many of which contain
relevant identification data, often in English. Twice yearly summaries of the
more important ones are contained within the pages of the Lacewing Recording
Scheme's newsletter, Neuro News. Access to these papers, however, is rather
easier for a specialist researcher than it is for the general entomologist who
simply wishes to be able to name the insect before him or her.