5
ESSEX LACEWINGS AND THEIR ALLIES
AN INTRODUCTION AND APPEAL FOR RECORDS
INTRODUCTION
The lacewings are soft-bodied, holometabolous insects ranging in size from a few
millimetres to around 10cms in length. The group includes the familiar green and brown
lacewings (Chrysopidae and Hemerobiidae), waxilies (Coniopterygidae), ant-lions
(Myrmeleontidae) Ascalaphids (Ascalaphidae), the giant lacewings (Osmylidae),
spongeflies (Sisyridae) and others in the order Neuroptera, together with the alderflies
(order Megaloptera) and the snakeflies (order Raphidioptera). Around 6000 species are
represented world-wide, with 300 or so of these in Europe. Of these, 69 are recorded in
Britain, though this total includes one which is certainly extinct and two more which are
probably so. For Essex, there are records of 41 species. Together with the four British
scorpionflies (Mecoptera), all of which are also recorded for Essex, the lacewings form a
convenient group for study.
Identification, however, has been rather problematical to date. There has been no major
review of the order since Frederick Killington's two-volume Ray Society Monograph in
1936 & 1937. This covered the Neuroptera only and is clearly rather out-of-date. The
1957 Royal Entomological Society Handbook by Lt. Col F.C. Fraser also included the
other three orders but is plagued by a large number of errors and is quite unworkable by
anyone who has no prior knowledge of the group. Some recent keys to selected "difficult"
groups of lacewings have been produced; I shall mention these at the appropriate points
in the text below. Of course, for German speaking entomologists, the 1980 two-volume
tome by messrs. Aspock, Aspock and Holzel is strongly recommended (see references,
below).
ESSEX MEGALOPTERA - ALDERFLIES
Sialis lutaria - the common alderfly - is the only one of the three British species so far
known to reside within the confines of the Essex boundary. It is probably a familiar sight
for most naturalists, typically emerging from its aquatic stage during May, when literally
thousands may be disturbed from reeds and other emergent vegetation on which they are
resting whilst their wings harden and dry. Slow or stationary waters with oodles of ooze
are required to support the insect (the scientific name is derived from the Latin lutum =
mud). Sialis fuliginosa is unlikely to present in the county, though it should nevertheless
be looked for alongside faster-flowing rivers. S. nigripes very possibly is present; it may
have a preference for chalky areas. Identification of alderflies requires an examination of
the genitalia (both sexes) and the reader is referred to the illustrations by Plant (1989).