List of the Insect Fauna of the County. 113
Gall-makers are found amongst two families of the highly
specialised Hymenoptera. A few sawflies (Tenthredinidae)
produce galls, but it is to the allied family Cynipidae that the
gall-flies par excellence belong. The life-history of the Cyni-
pidae is somewhat varied. It contains parasites (true mur-
derers), inquilines (true burglars), and gall-makers (true
house-holders).
The study of the imagos will be found somewhat puzzling
to the general entomologist, as there is a very general like-
ness amongst the species ; and even the cuckoo gall-flies, or
Synergi, which are inquilines (lodgers in galls), greatly
resemble the true gall-producers. In several instances Linne25
and other systematists have taken the one for the other. Other
genera of Cynipidae are parasitic on the Siricidae, on various
Diptera, and on plant-lice (Aphides); but it is with the gall-
making species only we are just now concerned. I will, how-
ever, take this opportunity of warning the student how
25 Of the 19 species of Cynips described by Linne (Syst. Nat.), 7 only
are true gall-makers, the other twelve being either inquilines or parasites.
Fabricius noticed 23 species of Cynips; many are referable to gall-
makers of other orders than Hymenoptera, and there the inquilines, para-
sites, and gall-makers are equally confused. Neither of these great
masters of Entomology referred to Malpighi's remarkably accurate de-
scriptions and figures in his 'De Gallis' (1686).
This note reminds me of a distinguished Essex gall observer, Rev. W.
Derham, D.D., F.R.S., &c, Canon of Windsor, and for many years Rector
of Upminster, in this county. In his 'Physico-Theology,' altogether a
remarkable series of sermons, or Boyle lectures (1711 and 1712), there
is much curious information about our Essex gall fauna. Part of one
note runs thus:—" Since my penning this I have met with the most
sagacious Malpighi's Account of Galls, &c., and find his Descriptions to
be exceedingly accurate and true, having traced myself many of the
Productions he hath mentioned. But I find Italy and Sicily (his Book
De Gallii being published after he was made Professor at Messina) more
luxuriant in such Productions than England, at least than the Parts about
Upminster (where I live) are. For many, if not most of those about us,
are taken Notice of by him, and several others besides that I never met
with ; although I have for many Years as critically observed all the
Excrescences, and other morbid Tumors of Vegetables, as is almost
possible, and do believe that few of them have escaped me......."—
'Physico-Theology.' Tenth Ed., p. 386, note z. (London, 1742).
O