Sept., igi/.] Marchand: Notes on Early Stages of Chrysops. 153 



The fly then proceeds to lay, beginning from the outer edges of the 

 egg-cKister obliquely downwards towards the lower end. Having 

 reached this, the abdomen finds no resistance to its movements, hence 

 it is withdrawn upwards, and a new series of eggs is laid parallel to 

 the former, or, more frequently, the abdomen is shifted to the other 

 side of the cluster, and here the following row is laid. Sometimes 

 the fly alternates regularly between the right and left side of the 

 cluster, spmetimes she may lay two or three rows of eggs on one 

 side, ending near the middle of the cluster at the lower extremity. 

 During oviposition, the female fly is rather quiet, and a leaf or stem 

 may be taken from the field to the laboratory together with the egg- 

 laying fly, as Hine has already stated. After about three quarters 

 of an hour the egg-mass is completed, and the fly darts off suddenly. 

 If disturbed, however, the flies often leave in the middle of the act 

 of oviposition. An egg-mass once abandoned is never completed, as 

 the fly does not return to the same leaf, and evidently has no means 

 for finding her egg-mass again, and no instinct of looking for it. 

 Flies which in a glass jar in the laboratory had continued to lay never 

 started laying again if they once had been disturbed and caused to 

 leave their egg-clusters, but acted like other captive Chrysops, which 

 I could never induce to deposit any eggs. 



In one case only, a female, having been disturbed in the occupa- 

 tion of laying, and having paused for a few minutes, started again 

 with movements of the abdomen, evidently in the intention to con- 

 tinue laying. However, having changed its position on the leaf but 

 slightly, it could not reach the egg-mass any more with the tip of the 

 abdomen; and after continuing for awhile to press the abdomen 

 against various places on the leaf, as if in search for the egg-mass, 

 it gave up and left. Apparently for each female it takes a long 

 preparation until a suitable place to lay the first tgg is found, while 

 to continue the egg-laying act the presence of previously laid eggs 

 is necessary. 



Since many females of Chrysops, in nature, leave the egg-mass 

 before it is completed, many of the clusters have only thei'r upper 

 half complete, while the lower half ends more or less obliquely trun- 

 carte or "diamond-shaped" (Hine). 



I have described the eggs of Chrysops callidus above, and recall 

 that the white coloration of the fresh egg-clusters is due to the pres- 



