WERNER MARCHAND 51 



and places eggs along it downwards until the apex is reached; then changes to 

 the other side of the V and places eggs along it, downwards to the apex on this 

 side. It was noted in specimens of this species that sometimes a female would 

 place as many as three rows of eggs on one side, one after the other, before chang- 

 ing to the opposite side. It is only necessary to study a mass of these eggs in 

 order to see the precision with which the different specimens are arranged. 



The eggs are placed on various aquatic plants, often standing in 

 rather deep water and at times as much as 20 rods from shore. Hine 

 always found them on scattering plants around the edges of grassy 

 areas and not back among the dense growth; consequently they are 

 easily seen, not only on account of their conspicuous location, but also 

 because of their shining black color, which contrasts strongly with 

 the green leaves to which they are attached. 



Their coloration renders the egg clusters conspicuous, and Hine 

 suggests that hand picking might be of consequence in the control of 

 Chrysops. In order to demonstrate what could be done in the way of 

 gathering eggs of this species, Hine went out on the morning of July 

 17, in Ohio, in a small rowboat, and collected for an hour. At the 

 end of this time a count showed 433 masses, and an average of 250 

 specimens to each mass, a result obtained by counting several and 

 striking the average, giving a total of 108,250 single eggs taken as a 

 result of the hour's work. 



Eggs of Chrysops mcerens, laid from 8.45 to 9.30 a.m. on July 13, 

 hatched before noon of July 19, thus making the incubation period 

 6 days. This is the shortest incubation period Hine has observed 

 for any species of Tabanidae. 



Of the larvae, Hine says that after hatching they drop into the 

 water, and he states that, in the natural breeding grounds of the 

 flies, it is almost impossible to find the very small larvae after they 

 have dropped from the eggs and have become more or less scattered 

 among the debris which is usually plentiful in these places. 



In order to ascertain whether the young larvae can be killed by 

 spreading a film of kerosene on the surface of stagnant water over 

 which eggs are placed, Hine (1906) performed some experiments. A 

 tank of water was used, on the surface of which half a pint of kerosene 

 was placed to each square yard of surface. Sparganium leaves to 

 which the eggs were attached were brought in from the marsh and 



