151 
on elm leaves May 17, and paired at midnight May 25. Our ob- 
served dates of copulation all fall within the month of May. 
The several species of May-beetles may continue active, in a nor- 
mal season, from one to two months, reckoning this period from the 
first appearance of the earliest specimens to emerge to the final disap- 
pearance of the beetles for the year. In our work of 1906 the dates 
of first and last appearance of the more abundant species in collec- 
tions made regularly near Urbana, at night, from willow, oak, elm, 
and Cottonwood (Carolina poplar), were as follows: L. implicita, 
May 13* and June 28 (46 days) ; L. ilicis, May 21 and June 23 
(33 days) ; and L. hirticiila, May 23 and June 18 (26 days). In 
New York, on the other hand. Professor Slingerland some years 
ago obtained L. fiisca in his light-traps from May 6 to July 5, 1889, 
and from May 26 to June 28, 1892 ; L. dubia from May 8 to July 5, 
and from May 30 to June 22 ; and L. ilicis from June i to July 30. 
Capturks of Lachnosterna at Light-traps, Open 
Fields, Urbana, 1906. 
May 26. 
May 31, 
June 2. 
June 4. 
June 6. 
June 9. 
June 15. 
June 18. 
June 20. 
June 23. 
Total . . 
a 
rt 
rt 
[fl 
a 
'J 

> 
a 
3 

2 
4 
4 
6 
1 
1 
5 
8 
3 
5 
6 
1 
3 
4 
8 
2 
3 
4 
18 
1 
1 
2 
7 
2 
25 
22 
5 
24 
16 
9 
1 
15 
1 
40 


76 
21 
3 
5 
34 
3 
115 
Collections made only from the food plants commonly show a 
more rapid diminution and earlier disappearance of males than of 
females. We may take as an example 2517 specimens, of L. implicita 
collected from trees on twenty-six different nights between May 14 
and June 28, 1906. Thirty-nine per cent, of the specimens taken 
during the first thirteen days were males and only 15 per cent, of 
those taken during the last thirteen days. On the other hand, in 
collections made during the same period by means of lantern traps 
*The spring was unusually late ttiis 5-ear, and May-beetles did not appear on the wing 
until May 13. 
