1907.] 



White-geubs and May- Beetles. 



463 



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. Mrticula, May 23 and June 18 (26 days). In 

 New York, on the other hand, Professor Slingerland some years 

 ago obtained L. fusca in his light-traps from May 6 to July 5, 1889, 

 and from May 26 to June 28, 1892 ; L. diihia from May 8 to July 5,' 

 and from May 30 to June 22 ; and L. ilicis from June i to July 30. 



Captures of Lachnostern-a at Light-traps, Open 

 Fields, Urbana, 1906. 



Collections made only from the food plants commonly show a 

 more rapid diminution and earlier disappearance of males than of 

 females. We rriay 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 



*Tlie spring was unusually late this year, and May-beetles did not appear on tlie wing- 

 until May 13. 



