146 
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 Alay-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 daytime 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 
3^ear. 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. 
II 
