THE POTATO TUBER MOTH. 
25 
REPRODUCTION. 
Mating takes place within a day or two after emergence. During 
the summer months 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 in the field, generally under clods and rubbish, at 
temperatures of from 59° to 65° F. 
Oviposition takes place within 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 moths 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 discovers a narrow deep crack in the tuber 
the eggs are often placed within it in a chain. When the breeding 
jars are covered with cheesecloth it is always found that some eggs 
are deposited on the cloth. This is in corroboration of the fact stated 
by Picard (83), that oviposition is stimulated by a roughened surface. 
55889°— Bull. 427—17 4 
