458 Bui^LETiN No. 116. [August, 



we now know, to the immediate neighborhood of its origin. The 

 grubs change location slowly as their food is exhausted, and injured 

 spots in an infested lawn or grain field will gradually enlarge in all 

 directions, the white-grubs moving outwards into fresh pasturage 

 as the infested vegetation dies from the destruction of its roots. The 

 grubs also sometimes gather in from all directions towards a par- 

 ticularly attractive patch of their food plants ; but there is nothing 

 to show that they move from place to place by definite underground 

 migration, or that they cover any considerable distance, such as to 

 take them from one field to another, during the whole period of their 

 active larval life. 



The May-beetles also seem local in their distribution. Although 

 very good fliers, they use their wings only to carry them from their 

 place of origin to the trees and shrubs on which they feed and in 

 which they copulate at night, and from these to their da)rtime hid- 

 ing places, never moving in swarms, so far as known, or migrating 

 over considerable distances. There is, in short, no evidence of any 

 migration movement of this insect in any stage or under any cir- 

 cumstances, but each locality or considerable neighborhood prob- 

 ably breeds and maintains its own white-grub population year after 

 year. Their most marked movements are the evening flight of the 

 beetles to their food plants, and- the morning dispersal from trees 

 to the fields in which the females lay their eggs. 



The discovery that certain species, at least, of the May-beetles 

 may feed, and sometimes do feed to a small extent, on corn and 

 grass, and the consequent conclusion that they may not need con- 

 venient access to trees for food, raises the important question 

 whether some of these insects, and possibly certain species of them, 

 may not live continuously in the fields, feeding on the crop plants 

 there and laying their eggs in the very places where they themselves 

 originated. If this is the case, collections made in the fields at max- 

 ii'.ium distances from trees should give us proof of the fact; and I 

 consequently arranged, in the spring of 1906, for the systematic use 

 of lantern traps distributed over an open area of one hundred and 

 sixty acres on the main farm of the University of Illinois, with trees 

 of various sorts in a cemetery along one side of this tract, and no 

 others within less than half a mile from it in any direction. These 

 traps were ordinary kerosene lanterns, with glass globes, placed 

 over large tin trays, each containing kerosene to a depth of about 

 half an inch. These trays were not large enough to secure all the 

 beetles which flew against the lantern globes, but they nevertheless 

 gave satisfactory samples of the beetles flying in the field. 



