220 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



iug the night as during the day. Gerstaecker remarks of the European 

 migratoria that it feeds most at night. 



As the insects advance in age the roosting habit becomes greater, 

 and for a few days after getting wings the mature insects delight to 

 gather away from the ground, especially on trees. 



INTERVAL BETWEEN ACQUIRINa FULL WINGS AND EGG-LAYING. 



This will of course vary according to surrounding conditions, and may 

 be said to average from two to four weeks. Exact data are with great 

 difficulty obtained, since it is always impossible to know the exact age 

 of winged insects when captured, and the species is not easily reared 

 from the immature states in confinement, especially east of its natural 

 range. Mr. Whitman, who at Saint Paul, Minn., is just within its range, 

 has made the only exact experiment that bears on this point, and gives 

 it in the following words, in his special report for 1876 : 



On the 25th of June I shut np in wire-gauze cages nine pupce of the Rocky Mount- 

 ain locusts. The bottoms of the cages were filled with earth packed hard, and the 

 insects appeared to thrive in confinement. By the 2d of July they had all become 

 perfect insects. By the 8th of July they commenced coupling, and were seen repeat- 

 ing the act for several days. On the 15th and 16th, two of the females went through 

 the form of depositing eggs, and I marked the place of deposit on the edge of the cage. 

 The coupling was repeated again as before, until the 3d cf August. At that date the 

 coupling ended, and the locusts became almost inactive, and were seen to eat very 

 rarely afterward. 



The following facts from notes made by us on other species common 

 around Saint Louis, will also throw light on the subject. In two in- 

 stances where the eggs were obtained from the same individuals that 

 were observed to go through the last molt, the interval varied from 

 about one to three weeks in species of the same genus j while in the 

 others, which are approximately correct, it varies from one to six weeks. 



Caloptenus atlanis, Riley; — Mature insects first noticed July 12. Eggs deposited July 18. 



C. femur-rubrum, Burm. — Became winged August 29. Eggs laid October 3. 



C. lurida, Dodge. — First winged insects captured August 25. Eggs deposited Septem- 

 ber 17. 



C. hivittatws, (Say.) — First winged insects noticed July 7. Eggs deposited August 31. 



C. differeniialiSf Thorn. — First winged specimens obtained July 19. Eggs laid Septem- 

 ber 9. 



Pezofettix viola, Thorn. — Mature insects first noticed August 18. Eggs laid by same 

 specimens on the 24th of August. 



P. nnicolor, Thomas. — Attained maturity about the Ist of September. Eggs laid by 

 same specimens on the 24th same month. 



Chrijsochraon, viridis, Scudder. — Mature insects first noticed July 7. Eggs deposited 

 August 20. 



Tragocephala viridifasciata, Goze. — Mature insects captured May 2. Eggs deposited 

 June 11. 



CEdipoda Carolina, (Linn.) — Mature insects captured July 12. Eggs deposited August 6 



O. sulphurea, Burm. — Mature insects captured September 19. Eggs deposited Sexotem- 

 ber 28. 



0. pJicenicoptera, Germ. — Mature insects captured June 20. Eggs deposited July 13. 



