50 William B. Herms 



Egg Deposition 



Lucilia caesar deposits eggs in irregular masses on the softer 

 portions of the fish, e. g., around the eyes, around the anus, be- 

 tween the gills, on an abrasion, or on the underside of the carcass. 

 This is due to the presence of much liquid food at these particu- 

 lar portions, which the adults suck up while depositing eggs. 

 Whether the deposition of eggs is associated w^ith the stimulation 

 of the food within the alimentary canal of the female is discussed 

 in Chapter VI. The deposition of eggs on these softer portions is, 

 however, an adaptation favorable to the larvae, since they can thus 

 immediately gain easy access to the body cavity. The gill slits 

 offer good receptacles for eggs, and into these they are pushed by 

 means of the protruded abdominal segments, the open mouth and 

 opercles of the fish affording a good entrance. 



Eggs are also commonly deposited on the upper side of the 

 carcass while the fly excitedly flits about sucking the juice. In 

 this way great masses accumulate on the large fish, sometimes 

 one mass growing to the size of a walnut. Several times the 

 mouth and gills were masked with a cloth to watch the effect. 



O 



This resulted in eggs being laid on the cloth and even on the loose 

 ends of the string with which the mask was tied. 



One female was observed to remain in the same position about 

 six minutes, w^ith abdominal segments pushed into a fold of the 

 cloth mask just mentioned. At the end of this time between 

 ninety and a hundred eggs were laid. From among a number of 

 flies taken on a dead fish, a large female (72 mg. in weight) was dis- 

 sected to ascertain the number of eggs contained within the ovaries. 

 Two hundred and forty-seven fully developed eggs were taken out 

 and the dissected ovaries showed no trace of immature ova. The 

 great w^eight and distended condition of the female would indi- 

 cate that few if any eggs had been deposited. How the above 

 number compares with the normal number of ova produced by a 

 single female of Lucilia caesar, the writer cannot say. This 

 matter should have further investigation. 



Sarcophaga sarraceniae deposits living young and deposits them 

 anywhere on the carcass or even near it, compelling the young 



