60 NEW YORK STATE MUSEUM 



approach of cold weather and remain until the following spring. 

 In July of the third summer they construct oval cells and change 

 to pupae, the latter transforming to beetles the following August 

 or September and the perfect insects appearing during May and 

 June of the next year. 



Natural enemies. White grubs are most acceptable prey to 

 pigs and also that much avoided and generally abused animal 

 known as the skunk. Both dig in badly infested fields and swine 

 are generally credited with being exceedingly efficient destroyers 

 of these pests. They will frequently root up and devour prac- 

 tically all the grubs in badly infested areas to which they have 

 access. 



Crows are well-known enemies of the white grub. Mr William 

 H. Wanzer of Slingerlands reported that in his locality these birds 

 had discovered the infested areas and were digging out and de- 

 vouring the grubs in grass and potato fields. Similar operations 

 have been observed in Illinois, while studies by Dr F. E. L. Beal 

 in 1894 showed that crows ate either beetles or grubs in every 

 month from March to October inclusive. Blackbirds are also re- 

 ported as feeding upon the grubs. 



A common parasite of the white grub in Illinois is known as 

 Tiphia inornata Say. The cocoon of this species is oval, 

 brown and about three-quarters of an inch long. It is easily recog- 

 nized by the slight neck or constriction at one extremity. These 

 cocoons were found in small numbers in one infested field in 

 Schodack. Another large parasite known as Myzine sex- 

 cine t a Fabr. also preys upon the white grubs and forms a co- 

 coon similar to that of the Tiphia noted above, though differing 

 in their greater smoothness and lacking the loose, fluffy coating of 

 silk. This species, according to recent investigations, appears to 

 be fully as efficient a parasite as the Tiphia. Another parasitic 

 Hymenopteron which has been reared from white grubs is 

 Ophion bifoveolatum Brulle. The genus Ophion is 

 rather common in New York State and there is no reason for think- 

 ing that other species may not prey at least occasionally upon the 

 white grub. 



A number of parasitic flies also depend in considerable measure 

 for sustenance upon white grubs. A bee fly, Sparnopolius 

 f u 1 v u s Wied. has been reared in Illinois from white grubs, and 

 the same is true of the peculiar Pyrgota undata W r ied., a 

 species which unfortunately seems to be not very abundant in New 



