1907.1 White-ghubs and May-beetles. 477 



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 quick 

 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 crpps by white-grubs and May-beetles are often of the 

 most serious and extensive character. The beetles by their destruc- 



