18 BULLETIN 1238, U. S. DEPARTMENT OF AGRICULTURE 



one male in 1920. In 1920 females were to be found in the field for 

 10 days before any males could be found. C. V. Riley, in his 

 Seventh Report on the Insects of Missouri (17), noted that the 

 females outnumbered the males, and the following year (20) stated 

 that out of 58 reared specimens 56 were females. Other writers 

 have mentioned this seeming preponderance of females, which is at 

 present unexplained. 



ACTIVITY OF THE MOTHS. 



The greatest activity of the moths occurs just at dusk, although 

 they continue to be more or less active during the night, and oc- 

 casionally to a very limited extent during the daytime, especially 

 if the day is dark and cloudy. During the day the moths are for 

 the most part quiescent, the females often passing the tune in the 

 more or less protected places on the trunks of the trees. The winged 

 male moths may pass the day in similar locations, and are also likely 

 to be found in the grass and debris at the base of the tree. 



With darkness a period of great activity begins if the weather is 

 mild, and during this period mating usually takes place, although 

 mated pairs are to be found throughout the night, and occasionally 

 during the day. Moths in coitu have been observed at different 

 times, but the male moths usually seem to pay comparatively little 

 attention to females which have been fertilized and have been laying 

 eggs. 



PREOYIPOSITTOX PERIOD. 



The length of time elapsing between the emergence of the female 

 moth and the deposition of her eggs varies greatly, depending chiefly 

 on weather conditions and upon whether the female has mated. 

 During very cold weather the upward progress of the moth is very 

 slow, and a number of days may elapse before egg-laying com- 

 mences. Unfertilized females will lay only a very few scattered 

 eggs. In 1920 a total of 20 females which emerged between October 

 28 and November 7 were placed in a wire cage in the insectary yard. 

 November 10 one male was added, but apparently escaped or died, 

 as it could not be found the following day. The day this male was 

 placed in the cage a few scattered eggs were laid, but no more were 

 found for more than a week. On the 18th six males were collected 

 in the field and placed in the cage, and on the following day eight 

 egg clusters were deposited. In this case the minimum preoviposi- 

 tion period was at least 12 days, oviposition evidently having been 

 delayed pending the arrival of the males. On the other hand, a 

 preoviposition period of slightly more than 24 hours has been noted 

 in a number of instances, and under favorable conditions this period 

 is usually less than three days. 



Table 8 gives data in connection with the oviposition of IT fe- 

 males isolated in battery jars in the insectary. Males were collected 

 in the field, as none were available from the soil cages. It is not 

 known why two of the moths (Nos. 3 and 17) delayed so long before 

 laying their eggs. The average preoviposition period as calculated 

 for these particular individuals has little significance, the length 

 of this period being so very dependent on weather conditions, which 

 are extremely variable in the late fall and early winter. 





