THE MARGUERITE FLY. 37 



together totaling from 70 to 81. The eggs deposited after the third day 

 of the oviposition period failed to hatch for some reason. As it was rather 

 difficult to make out the eggs on thif particular plant, and made more 

 difficult some days because of poor Ught, the number of eggs counted in 

 all probability falls short of the actual number laid. The daily record was 

 'as follows: — 



14 ^5 



5-19-16-4-1-4-5-5-1-2-1-1-6-3-.3 ^ 



As in the first case, the upper figures represent the doubtful ones. 



This female deposited the greatest number of eggs for a single day the 

 second or thu'd day, and she deposited at least half of the total during the 

 first three days of the oviposition period. In this case, as in the first, the 

 great bulk of the eggs was laid during the first half of the period. 



In other cases newly emerged \'irgin females were confined with males 

 in cylinder jars until they coupled. As soon as they separated, they were 

 isolated on plants, one female on a plant, in cages in the insectary. New 

 males were introduced from time to time to insure fertilization. Of the 

 three females thus confined, however, only one was successfully carried 

 through a complete egg-laying period. In this case the pupae produced 

 were counted, as it was impossible to count either the eggs or larvse without 

 allowing the female to escape; the number counted was 132. 



Length of Adult Life. 



In these experiments, as in some of the others, cheesecloth bags were 

 again made use of, males and females together, and females by them- 

 selves, being confined \Adthin the bags upon leaves on plants in the labora- 

 tory. In all cases, except one in which a male lived as long as a female, 

 the females lived longer than the males, the length of life of the males 

 ranging from four to thirty days, while that of the females ranged from 

 eleven to forty-seven days. In a number of cases the segregated females 

 lived much longer than those confined with males, their length of adult 

 fife ranging from eleven to sixty-seven days. 



Whether the phenomenon of the longer life of some of the females kept 

 by themselves was merely a coincidence, or whether it was due to their 

 not having the opportunity +o ma<e, the writer is unable to say, in absence 

 of more extensive data. 



In absence of food, the greatest longevity — the usual (a single indi- 

 vidual lived four days) — ■ was three days. 



The Egg. (Plates I. and II., Figs. 3, 5.) 



The egg is colorless, somewhat cloudy; smooth; elongate oval, though 



rarely oval, somewhat broader towards one or the other end, more often 



towards the posterior, and, a? a rule, more bluntly rounded at the anterior 



end ; a compound microscope reveals a gelatinous cap at the anterior end, 



