150 
These data are of special importance as showing the time of 
night when the beetles are accessible in the trees on which they 
feed — a subject important to a discussion of measures of prevention 
and remedy. 
Habits ov Reproduction. 
With respect to the reproduction of May-beetles, we need to 
know at what time of day, in what situations, and especially how 
soon after emerging, the sexes pair, and when, where, how soon, and 
in what numbers the females deposit their eggs. Our definite infor- 
mation as to the pairing of the beetles is not abundant, but is suffi- 
cient to show that they pair at night on their food plants. The males 
are mucli more active than the females, — a fact illustrated by their 
greater abundance at lights in fields at a distance from trees. In 
the product of the light-traps used in 1906, as described in this paper 
under "Mo\'ements of ^Migration and Dispersal"' pp. 146-148), 
the males outnumbered the females about 4 to i, while in collections 
made at the same time from trees the number of males was only 
39 per cent, of the total number taken. Similar data were given 
in my Seventh Report.* It will be seen that it does not follow from 
the greater number of females taken on the food plants that females 
are actually more numerous than males, but only that the latter are 
more widely scattered at night, and more generally on the wing. 
It has been noticed by some of the office assistants, and par- 
ticularly by Mr. J. A. West, that May-beetles are sometimes very un- 
equally numerous in neighboring trees of the same kind, one tree 
containing a buzzing multitude while there are comparatively few 
on another tree of the same species close by. I have myself once 
seen a large tree so full of May-beetles in the evening that the noise 
of their movements was like that of a huge swarm of bees, although 
the condition of the leaves the following day showed that they had 
not resorted to this tree for food. Their assemblage in tree-tops is 
evidently in part for breeding purposes, and not wholly for food. 
About fifty pairs of these beetles have been taken by us in 
copula, all but three of them from trees at night. In one case a pair 
of L. rugosa was captured at night by Mr. West from a grass-blade 
in a pasture, and two pairs of L. invcrsa have been seen copulating 
in a breeding-cage, also at night. These two pairs had been taken 
from earthen cells in the ground October 5, 1905, and transferred to 
the insectary, where they at once went into the earth, first appearing 
above ground on the ist of the following May. They began to feed 
♦Eighteenth Rep. State Eiit. 111., p. 117. 
