SILVER Y-MOTH. 59 
But as a really destructive infestation of our crops it is rarely 
mentioned, the great exception being the memorable immigration into 
this country in the year 1879, in which the swarms left North Africa 
in April, and, after traversing Europe, and doing plentiful mischief by 
the caterpillar infestation they gave rise to by the way, they arrived 
on our south coast early in June, and the moths were subsequently 
observable throughout England, Scotland, and Iveland.* The cater- 
pillars did great mischief in various places; but it is worth notice that, 
notwithstanding the great prevalence of the infestation in 1879, in the 
the following year it was merely reported as being noticed in small 
numbers and in few localities. One very especial example of this was 
at Exeter, where, in 1879, Mr. Edw. Parfitt (who was a skilled ento- 
mologist) mentioned that he ‘‘never saw anything to be compared 
with its numbers; towards the end of September the larve literally 
swarmed on every garden plant, defoliating the plants, as well as 
riddling the leaves’’; and in the following year Mr. Parfitt observed 
that up to the 17th of September not a single specimen had been seen 
in the neighbourhood of Exeter. 
PREVENTION AND Remepy.—As this attack so rarely occurs, measures 
of preventing it seem hardly to require to be entered on. Still it 
would perhaps be desirable where cocoons are noticed in the great 
numbers mentioned at p. 57, to have these collected and burnt. This 
small amount of trouble would ensure that there should be no re- 
currence of attack, in whatever state the infestation may pass the 
winter with us, from development of the contained chrysalids. 
In garden attack, dustings with lime and the customary deterrent 
dressings would be sure to be beneficial; and as the caterpillars are 
large, hand-picking might be a very serviceable remedy at no great 
cost; also, as the caterpillars appear very sensitive to the effects of 
wet, heavy washings or syringings of cold water would be likely to get 
rid of many of them. 
* For many details and dates of observation, for which I was obliged to Mr. E. 
A. Fitch, F.E.S., of Maldon, Essex, see, amongst other contemporary records, my 
own Annual Report for 1879. 
