210 THE ENTOMOLOGIST. 
A PuaGur or CaTERPILLARS.—I was interested to see Mr. Adkin’s 
reply—‘ Entomologist,’ August, 1916, pp. 191-2—to a contribution 
which appeared in the ‘ Entomologist’ (and elsewhere) for last July. 
I believe it is generally agreed upon by scientific economic entomolo- 
gists that the right course to pursue in combating any insect pest is 
to parasitise it vif possible, and that “ spraying” and ‘ washes” 
belong to the realm of departmental and popular entomology. Spray- 
ing in the case of a greenhouse, or a particular tree, or with respect 
to some kinds of moulds, if repeated may possibly be a palliative, 
but in how many cases where spraying is adopted is the slightest 
trouble taken to establish ‘controls,’ and thereby endeavour to 
ascertain whether relief from any particular pest is brought about 
not by reason of the spray or wash, but irrespective of it, by purely 
natural causes? It must be obvious to anyone that, in the case of a 
large forest tree—especially the larger-leaved kinds—however effec- 
tive the spray atomiser may be, and however sovereign the liquid 
sprayed, there must be hundreds of leaves which receive no more 
than a microscopical droplet on one side of the leaf only, and 
hundreds of larva, which, owing to the fact that they rest unexposed 
during the daytime, cannot possibly be touched by the spray, and 
how many leaves and larvee would escape untouched if, say, 10,000 
acres of forest were tackled? It may be said that the spray, even if 
it does not actually come in contact with the larve, renders their 
food-plant poisonous or unpalatable, but my experience is that the 
larve—even on a small rose-bush that has been smothered with 
spray—can always find sufficient unsprayed food-plant, and, even 
supposing this not to be the case, what is to prevent the larva from 
dropping by a thread to seek fresh quarters, especially if polyphagous? 
Another point which appears to be lost sight of by the spray enthusiasts 
is that a spray does not discriminate betwixt friend and foe, and is 
quite as likely to affect beneficial as well as noxious insects, quite 
apart from probable destruction of bird life, the very thing one wishes 
to foster. As a general rule, Nature may be relied upon to suppress 
anything which is harmful, and those who put on the boxing-gloves 
with her generally ask for rough handling. In the case of the West 
Wickham Wood, cited by Mr. Adkin, and which I have myself 
visited regularly many times during the last fifteen years, I very much 
question whether the ravages of the larvae which were so much in 
evidence this year, were not of indirect benefit to the wood, quite 
apart from the warblers, which were abundant there this year. Light 
and air were admitted to the undergrowth of plants and bushes, and 
possibly members of the insect life which parasitises the defoliating 
larvee were increased thereby. At the present time the undergrowth 
looks in better condition than I have seen it for years, whilst fresh 
foliage has appeared on the infested trees. The predominant larvee 
in this wood this year were those of 7. viridana, but a large per- 
centage of the pupe disclosed parasitic flies —G. Bertram KrrsHaw 
M.Inst.C.E., F.E.S.; West Wickham, Kent. 
AGRIADES CORYDON ATTACKED BY A Bua, ZIcRONA CHRULEA, L. 
—Whilst collecting A. corydon at Royston on August 9th, 10th, and 
11th, with my friends, Messrs. F, Pennington, W. Brocklehurst, and 
