4 
POPULAR SCIENCE REVIEW. 
we are still unable to supply a remedy against its attacks, yet 
it is obvious tbat every attempt to provide against tbe ravages 
of any insect is little likely to prove efficacious until tbe 
economy of tbat insect is made known. We must first be 
sure of tbe disease before we can apply tbe remedy. And 
bere let me remark tbat tbis department of Agricultural 
Science is eminently indebted to tbe late Mr. Jolin Curtis, 
wbo bas studied through a long period of years tbe habits 
and life-bistory of a vast number of insects injurious to our 
field crops. The results of these valuable investigations have 
been published in tbe “ Transactions of tbe Entomological 
Society - ” and tbe “ Quarterly Journal of Agriculture,” and 
conveniently methodized in bis beautiful work on “ Farm 
Insects,” published by Blackie & Sons in 1860. To what 
Mr. Curtis bas written on tbe subject of insects injurious to our 
turnip crops, I have on tbe present occasion nothing new to 
record, but tbe naturalist takes delight in verifying by personal 
observation the investigation of his predecessors. 
To tbe unobserving, tbe apparently sudden appearance of 
myriads of insects is unaccountable ; hence people sometimes 
call in the direct agency of tbe east wind, and attribute to 
tbat much-abused quarter tbe power to engender, by some 
mysterious influence, whole hosts of countless myriads of 
flies. Tbis is termed a blight , — a term which expresses in 
vague language nothing clearly intelligible, so far as relates to 
tbe direct cause of the mischief tbat ensues. Now tbe 
Haltica nemorum is probably known to, and seen by, farmers 
only at tbe time when tbe turnips are putting forth their 
smooth leaves. Fie bas not noticed them at other seasons of 
tbe year, and wonders where in tbe world they could all 
have come from so suddenly, with destruction on their wings. 
But tbe naturalist notices them even as late as November, 
sitting with bind legs bent under their bodies ready for a 
spring, upon tbe leaves of the plants. He notices, too, tbe 
various boles made in tbe fully- developed leaf, and witnesses 
tbe little enemy busy at work, in tbe very act of making 
them. But we must tell tbe short history of their lives in 
a few words. Tbe sexes pair from April to September. 
According to tbe investigations of Mr. Le Keux, the eggs, 
which are laid about one each day, are deposited on tbe under 
side of tbe rough leaves of the turnips. They are batched in 
ten days, when a small maggot, of a yellow colour, appears. 
He immediately begins to eat bis passage between tbe 
cuticles of tbe leaf, then bides himself in tbe ground, and 
changes in about six days to a chrysalis, the perfect insect 
emerging in about a fortnight afterwards. This little pest is 
widely distributed over tbe whole country, and is abundant in 
