165 
Relations to Agricultural Management. 
Injuries by white-grubs are- influenced to a considerable extent 
by the system of farming, and especially by the succession of crops ; 
by the management of pasture-lands, in which, if left wholly to 
themselves, they are likely to accumulate in increasing numbers year 
by year ; and possibly, also, by the time of the year when infested 
lands are plowed. While the old idea that white-grubs are essen- 
tially insects of pastures and meadows has been exploded by ob- 
servations of recent years, it still remains true that, other things 
being equal, they are most abundant in grass-lands, and consequently 
most injurious to other crops if these follow within one or two 
years upon an infested pasture or meadow. They seem particularly 
liable to accumulate in an old turf .which has lain unbroken for sev- 
eral years, and are less likely to be destructive where there is a c[uick 
rotation of crops, including a short period in grass, to be followed 
by one or two years in clover. The modern stockman's practice of 
herding cattle and pigs together is an excellent one from our stand- 
point, since the pigs, in following the cattle, are likely also to search 
out the grubs in the turf and to keep the sod practically free from 
them. 
It is a matter of common, though not universal, opinion among 
farmers who have watched the work of the white-grubs that fall 
plowing of infested lands is preferable to spring plowing. In the 
absence of any apparent reason why this should be so, and in the 
absence also of any experiments upon the subject and of any consid- 
erable number of exact observations, this supposition must be re- 
garded as doubtful. Our own field reports give thus far but a single 
instance, reported by Mr. Kelly in 1905, of a notable difference in 
white-grub injury corresponding to a difference in the time of plow- 
ing of different parts of the same field; and this instance is by no 
means clear, since there was injury by grubs in both parts of this 
field — much greater and more extensive, however, on the spring 
plowing. The white-grubs were also reported as less abundant in 
the part of the field plowed in fall, averaging there one grub to the 
hill of corn as compared with seven to the hill found in the part 
plowed in spring. The data of this observation are incomplete, how- 
ever, and this difference in number of grubs may have been due to 
something else than difference in the time of plowing. 
Injuries to Crops. 
Injuries to crops by white-grubs and May-beetles are often of the 
most serious and extensive character. The beetles by their destruc- 
