Ninth Report of the State Entomologist 355 



•with certaint}', when fields infested with these larvsB may or may not 

 be with safety planted to another crop. 



For many years past we have been told that the grub of the May or Jv^ne 

 beetle required three years for its maturity. The most particular state- 

 ment of its transformations was that given by Professor Riley in his \st 

 Report on the Insects of 3Iissouri, in 1869. According to this, the 

 ■eggs were laid in the ground after the pairing of the beetles, and 

 hatched in the course of a month. The grubs attained their full size in 

 the early spring of the third year, when they changed to pupae, and soon 

 thereafter to beetles, emerging from the ground in May. " Under 

 favorable conditions it is probable that some of the grubs became pupsB 

 and even beetles in the autumn, subsequent to their second spring," but 

 remained in the earth until the following spring. 



In correction of the above. Professor Forbes has given as the result 

 of his studies upon the white grubs in Illinois (where thirty-one species 

 are known to occur), and more particularly upon six of the most abun- 

 dant and most destructive species, viz., Lachnosterna gibbosa, L. 

 inversa, L. fasca, L. rugosa, L. impUcita, and L. hirticula — the fol- 

 lowing as their life-history, quoting his carefully considered words: 



" It is not too much to say concerning the six species above, and quite 

 possibly of all the others, that they lay their eggs in June and early 

 July; that these eggs hatch in from ten days to two weeks; and that 

 the grubs live in the earth for a number of j^ears unknown, but seemingly 

 at least for two; that they may begin to pupate as early as the middle 

 of ,Iune [late spring, but pup;E may be found until September 5th] of 

 the year when they become full grown, aud may form the first imao-o 

 in the earth by the middle of August and the last as late as the middle 

 of September [all in summer], but that they very rarely, if ever, pass 

 the winter in the pupa state. They form the adult in this latitude in 

 late summer and early fall, and escape from the earth the following 

 spring and early summer * * * in April, May or June, or rarely 

 in July." 



Presuming, as it seems we may do, that there is a year in which the 

 Lachnosteruas deposit their eggs, — identical with the years in which the 

 beetles appear, and that these are separated by a term of years (probably 

 three), instead of there being deposits of eggs in successive years, givino- 

 grubs of various sizes and ages in the same field, — we may educe from 

 the above statement of life-history the following: 



1. The age of grubs turned up in spring plowing, seemingly about 

 half-grown, can not positively be told; it is, therefore, uncertain 

 whether they are to cease from feeding the following spring so as to 



