454 



Bulletin No. 116. [August, 



fusca, but, unfortunately, as no comparable collections were made 

 in the intermediate years, the evidence is not complete. Westcott's 

 Maywood collections, already referred to, on the other hand, hint at 

 a two-year period for L. gibbosa. This species predominated over 

 fusca in 1886, as shown by records made on five nights, from the 

 26th of May to the ist of June, in a ratio of 3.6 to i, and again in 

 1888, in a ratio, as already stated, of 25 to i, but was much less 

 abundant than fusca in the intermediate year. 



Food and Feeding Habits oe the Species. 



The white-grubs and the May-beetles, larvae and adults of the 

 same insect species, differ totally in their food and feeding habits, 

 the grubs eating the roots of various kinds of plants and the beetles 

 eating the leaves of trees and shrubs. In the absence of any means 

 of distinguishing the species one from another in the grub stage, no 

 evidence has been obtained of any special choice, by any of the 

 species in this stage, among the various elements of the food of 

 grubs in general. So far as known, all of them may take, with 

 equal relish, all kinds of food which any one of them will eat. If 

 the different species of grubs do indeed make definite and varied 

 choice of food, the fact may be ascertained by breeding to the adult, 

 for determination, pupae and full-grown grubs obtained in various 

 situations near or among different kinds of food plants ; but there 

 is at present too little recorded information on this point to permit 

 us to infer any difference whatever in the choices of our more 

 abundant species. 



The species of beetles themselves, on the other hand, differ con- 

 siderably, although not sharply and completely, as a rule, in their 

 choices of food yrhere several kinds are equally accessible to them. 

 Evidence of these preferences has been obtained by us in three dif- 

 ferent ways : ( i ) by experimental feedings with beetles kept in 

 confinement; (2) by parallel collections of beetles made from dif- 

 ferent kinds of food plants; and (3) by the dissection of specimens 

 of various species, made to determine, by an examination of the 

 contents of their alimentary canals, what kind of vegetation they 

 have been feeding on. The first method shows what the beetles may 

 eat under stress of hunger, or perhaps with starvation as a penalty 

 for refusing what is offered them ; the second shows what the dif- 

 ferent species actually choose when a choice is open to them ; and 

 the third enables us to determine with certainty what the beetles 

 have eaten where direct observation is impracticable. The results 

 of our feeding experiments have been so different from those ob- 



