33 



(futilis, 45 percent, and inversa, 22 percent). Its next largest ratio 

 was 19 percent on willow, altho it was sixth of the willow May-beetles 

 in order of its relative frequency on that plant, and sixth also among 

 those taken on poplar. Furthermore, it was first among the small 

 numbers collected from the linden, second in the still smaller number 

 from hackberry, second also in our 71 collections from the ash, eighth 

 from the hickory, and twelfth from oaks. Elm, blackberry, ash, and 

 apple seem, from our data, to be its favorite foods. 



Pliyllophaga futilis Leconte 



Futilis was one of the moderately numerous species in Illinois 

 during our period, its numbers amounting to about 7 percent of all 

 our collections. It occurs thruout the state, but we have found it 

 less abundant in southern Ilinois than farther north. This and fusca 

 were the dominant or most abundant species at Aurora in 1908, and 

 were possibly more distinctly so than at the same place the following 

 year, altho our collections of these species in 1909 'were too small to 

 make this certain. Our data are not so distributed in time as to give 

 us any information concerning the length of life of the generation. 

 This is a rather early spring species, sometimes appearing even in 

 northern Illinois by the middle of April and in southern Ilinois be- 

 fore the end of March. It is also rather long-continued, not disap- 

 pearing as a rule in the central part of the state until July is well 

 advanced. Among the 1650 collections of May-beetles from the 45 

 food-plants which yielded our specimens, we found futilis in any 

 considerable number only on blackberry, apple, hackberry, elm, and 

 corn; but, curiously, 73 of 102 specimens from the four food-plants 

 in 1906 were from poplars. Sixteen hundred and thirteen of our 

 specimens were taken in 38 collections from blackberry bushes, and 

 331 in 58 collections from apple-trees. A larger proportion of futilis 

 than of any other species was taken from blackberry. In our list of the 

 fifteen most important May-beetles it stood first, also, on hackberry 

 and corn, second on elm, box-elder, birch, honey-locust, and goose- 

 berry, fourth on apple, ninth on willow, and thirteenth on oak. Its 

 numbers on ash, hickory, and poplar were each less than 1 percent 

 of the whole number of the species obtained from food-plants. The 

 collections from corn were made in a field which had been heavily 

 infested by white-grubs the year before, and the beetles, coming out 

 of the ground in early spring during a cool wet time, fed freely on 

 the young corn, to its considerable injury, without leaving the field. 



Futilis was evidently one of the species responsible for very heavy 

 crop injuries by white-grubs in northern Illinois in 1912, as shown 

 by its numbers there in 1914, when it yielded more than 17 percent 

 of all the northern Illinois collections contributed by Davis. 



