10 BULLETIN 432, IT. S. DEPARTMENT OF AGRICULTURE. 



to its normal position. The time occupied in oviposition varies from 

 10 seconds to 1 minute. The entrance to the puncture appears to be 

 left open, although frequently the epidermal tissue about the punc- 

 ture collapses, partly closing it. 



Only one egg is deposited in a puncture, but the fly repeats the 

 process of oviposition a number of times in a given day. Frequently 

 she oviposits into what are apparently small feeding punctures. 



The eggs of this species are not as easily detected by the naked 

 eye as are those of Agromyza parvicornis in corn, and A. angulata 

 Loew in timothy. They are more of a pale white than the eggs of 

 either of the other species and, consequently, are not so conspicuous 

 against the background. 



The flies feed and oviposit during all hours of the day. The ma- 

 jority of the eggs, however, are deposited between the hours of 11 

 a. m. and 1 p. m. during the time the adults are most active. 



Eggs may be deposited either from the upper or lower side of the 

 leaves, but the majority of them are deposited from the upper side. 

 They are placed with the longer axis of the egg parallel to the veins 

 of the leaves, as are the eggs of Agromyza angulata and A. parvi- 

 cornis. (PI. I, fig. 2, shows an egg in situ in leaf.) 



In the rearing cages eggs are deposited at or near the tips of the 

 leaves, along the margins, near or at the base, in the sheaths, and 

 sometimes in the upper part of the tender stems, especially in young 

 plants. In nature the eggs apparently are deposited at or near the 

 tips of leaves or along the margins of the lower leaves, as mines in- 

 variably are found to start from one of these points. 



EGGS DEPOSITED BY OXE IXDIYXDrAL. 



The females of this species, if they have been fertilized, begin to 

 oviposit in from one to six days after emerging from puparia; if 

 unfertilized, they do not usually oviposit. 



The laboratory observations of the senior author, made at Co- 

 lumbia, S. C, showed that a single individual deposited as many as 

 21 eggs in leaves of millet within a period of 21 hours. On an 

 average, nine eggs were deposited per day. The rate of oviposition 

 varied greatly and ranged from one or two eggs on a given day to 

 as many as 15 or 20 eggs on the following day. The maximum 

 number during the life of an individual was 1S8 eggs, and the longest 

 period of oviposition covered by one individual was 33 days. 



At Tempe, Ariz., Mr. TTildermuth recorded 105 eggs deposited by 

 a single individual in leaves of wheat in a period of 10 days. The 

 greatest number deposited in a single day was 27 eggs. 



In California the observations of the junior author showed 61 eggs 

 deposited in leaves of barley plants during the life of one individual. 



