THE POTATO TUBER MOTH. 



25 



REPRODUCTION. 



Mating takes place witliiii a day or two after emergence. During 

 tlie summer montlis this time may even be reduced. Sexual attrac- 

 tion is quite strong, the males being readily attracted to the females. 

 Pairs may mate several times, frequently promiscuously. Mating 

 is most common during the morning and evening. Mating pairs 

 have been noted m the field, generally under clods and rubbish, r.t 

 temperatures of from 59° to 65° F. 



Oviposition takes place witliin from 24 to 48 hours after mating. 

 Generally only a few eggs are deposited the first night, from 10 to 20 

 in number. The maximum number is deposited the second, third, 

 and fourth nights. Oviposition by a female when fed on sweetened 

 water may last for two weeks, but even in these cases it will be found 

 that over half of the eggs were deposited before the fifth night. 



The following record gives the oviposition record of an average 

 pair: 



October 7. — Pair mating. 

 October 8. — 7 eggs deposited. 

 October 9. — 31 eggs deposited. 

 October 11. — 57 eggs deposited. 

 October 12. — 39 eggs deposited. 

 October 14. — 34 eggs deposited. 



October 15. — 5 eggs deposited. 

 October 17. — 11 eggs deposited. 

 October 18. — 3 eggs deposited. 

 October 19. — eggs deposited. 

 October 22. — Female dead. 



Oviposition takes place almost altogether at night, especially 

 during warm nights. On cool dark days eggs are sometimes depos- 

 ited, but these are few in number and very seldom are two found 

 placed together. When the m.oths are kept in darkened cages they 

 deposit a few eggs during the day, but even here the greater part of 

 oviposition takes place at night. 



Adults in the act of ovipositing on potatoes were very commonly 

 noted. The female generally sought the eye of the potato and after 

 turning around a few times settled down and remained quiet for a 

 few moments. Just before oviposition the tip of the abdomen was 

 moved around slightly until a suitable place was found, then the 

 abdomen was contracted rapidly by drawing in the tip and the egg 

 was extruded. 



The egg when first deposited is viscid, and translucent white, but 

 hardens in a very short time. Generally the adult moves about 

 after oviposition until another satisfactory place is found, but the 

 same adult may deposit most of a night's quotum of eggs in the same 

 place. In case the adult (Hscovers a narrow deep crack in the tuber 

 the eggs are often placed within it in a chain. When the breechng 

 jars are covered with cheesecloth it is always found that some c^'gs 

 are deposited on the cloth. Tliis is in corro})orati()ri of the fact statcMl 

 by Picard (83), that oviposition is stimulated by a roughened surface. 

 55889°— Bull. 427—17 4 



