64 



Southern Species 



Foroesi: cherry, peach, and apple. 

 Micans: persimmon and oak. 

 Bipartita: willow, hickory, and oak. 

 Fraterna: oak, hickory, and persimmon. 

 Profunda: oak, hickory, and persimmon. 

 Crenulata: persimmon, willow, and hickory. 

 Corrosa: persimmon, oak, and hickory. 

 Delata: oak and hickory. 

 Forsteri: oak, hickory, and persimmon. 

 Praetermissa: oak, willow, and apple. 



Summary 



This paper presents a survey of the species, numbers, dates of 

 occurrence, food-plants, and Illinois distribution of the genus Phyl- 

 lophaga (May-beetles), based on a study of nearly 119,000 specimens 

 collected in forty- two counties in all but one of the nine years from 

 1905 to 1913 inclusive. 



Thirty-four species of May-beetles are recognized in Illinois. 

 They vary greatly in abundance, the above collection containing but 

 two specimens of the rarest species and 43,349 of the commonest. 

 Ninety-one percent of the specimens collected belonged to ten of the 

 species, the other 9 percent being distributed among the twenty-four 

 species remaining. 



A detailed discussion of the species, taken separately, shows for 

 each its numbers in each year and in each of the three sections of the 

 state, the dates, in each year, of its first appearance and its greatest 

 abundance, and its comparative numbers on each of its food-plants. 

 By means of the data of numbers and distribution, the dominant and 

 subdominant species are distinguished for each year and district, and 

 the intervals between their periods of greatest abundance are con- 

 sidered with reference to the length of the life cycle of the species 

 concerned. 



From a comparison of the May-beetles derived from northern, 

 central, and southern Illinois, respectively, it appears that three spe- 

 cies are practically limited to northern Illinois, three to the northern 

 and central parts of the state, two to the central and southern, and 

 eleven to southern Illinois. The actual boundary lines between these 

 areas of distribution are, however, irregular and meandering, espe- 

 cially that between southern and central Illinois, which is influenced 

 by the course of the streams, the southern species following them 

 northward towards their headwaters in a way to bring several such 

 species far into the central division of the state. 



The seasonal succession of the species — that is the order in which 

 they make their first appearance in spring — is worked out for each 

 section of the state as carefully as the wide distribution and irregular 

 time limits of the collections will permit. 



