8 
POPULAR SCIENCE REVIEW. 
destroying their friends ! Let them learn the following easy 
distich, which I improvise for the occasion : — 
Oh ! farmer, spare that bird, 
Touch not a single quill ! 
The rook is thy true friend ; 
Requite him not with ill. 
Instead of the last verse,, a little variety may be introduced 
by reading : — 
Of grubs he eats his fill. 
The choice of reading must be left to the poetic taste of the 
bucolic mind. 
The smother-fly, or plant louse (Aphis) must be enumerated 
as a very injurious insect to the turnip crops. The effects of its 
destructive work throughout a large portion of Shropshire, last 
August and September, were most remarkable. Crops that 
had survived the turnip -beetle and the caterpillars of Agrotis 
segetum and exclamationis , and seemed to be thriving, were 
suddenly attacked by myriads of Aphis, chiefly of the species 
A. hrassicce. In a few days, that which promised so well was 
hopelessly blighted. The leaves first curled and puckered 
inwards, then withered and died ; and the smell arising there- 
from completely tainted the air with a peculiarly offensive 
odour. Hardly a green turnip-field was to be seen for miles 
around ; nothing but dead leaves, which, in the distance, gave 
to the field rather the appearance of a brown fallow than a 
crop of turnips. 
As an illustration of the desirability of cultivating some 
knowledge of Natural History, and especially the economy of 
insects, I will mention that two farmers in this neighbourhood 
imagined that the lady-bird beetles ( Coccinella septem-punctata ) , 
of which in some fields I observed prodigious numbers, were 
the cause of much of the injury, and therefore slew as many 
as they could. “ What !" I exclaimed, “kill your friends 1 
don't you know that the lady-bird, both in its larval and adult 
condition, is a notorious consumer of aphis flesh?" Oh, no, 
of course neither the one nor the other had ever heard of such 
a thing. “Well, then," I said, “look here, on this leaf," and 
I showed my friend the little beetle engaged in the very 
act of dining off an aphis. 
The coccinellae are unquestionably very useful in this way, 
and it is a great mistake to destroy them ; but so innumerable 
were the armies of aphides in the autumn of 1865, that their 
well-meant endeavours to lessen the swarms were inappreciable. 
