THE MEL OL O NTH I DAL. 
273 
then the cold of the autumn may prevent the perfect insect from 
leaving - its cell — so that it does not fly until the spring of the third 
year. The larvae are shaped like those of the Scarabceidce gene- 
rally, and they are remarkable for their strong mandibles, which 
are furnished with a diamond-shaped tooth that enables them to 
cut across rootlets very easily. 
It would appear that the larvae of the May bugs, found as 
they are over the whole of Europe, were not formerly such pests 
to farmers. They were certainly not so common in the olden 
time, but they appear to have increased their numbers with the 
spread of agriculture. Farming operations favour these creatures, 
for they cannot live in undisturbed ground ; they cannot move 
about in solid earth or in old rocks, but they can do so in alluvial 
soils, or in those which the process of tillage renders light and 
suitable for vegetation ; and, formerly, the a'creage of cultivated 
ground where the May bug larvae can live was, of course, much less 
than it is now, and consequently the beetles were not so common. 
The larvae must be dug up to be destroyed, and this is a very 
awkward operation whilst ploughing and spade husbandry are going 
on. It is much easier to collect the beetles themselves, and if they 
were well hunted down everywhere simultaneously, there would 
be no doubt about a rapid diminution in the numbers of the larvae ; 
but, unfortunately, all the efforts of men who are sufficiently 
enlightened to advise the farmer rarely meet with success. Thirty 
years ago, a Prefect in the Department De la Sarthe — M. de 
Romieu — took great pains, and persevered in urging upon agri- 
culturists to destroy the real originators of the mischief they 
suffered from ; and of late years M. Riset has been studying the 
amount of mischief these creatures really commit. He found that 
in two arrondissements in the Department of Seine Inferieure, 
360,000 lbs. weight of cockchafer grubs were found ; and as a 
grub only weighs about thirty-one grains, there must have been 
8 1,290,322 of them. 
With this calculation before us, which refers only to two small 
districts, it is not difficult to understand the enormous amount of 
injury that i$ done to agriculture by these grubs. Very fortunately 
rooks, jays, magpies, crows, and other birds, eat immense quan- 
tities of them, and this fact alone ought to make us careful of 
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