10 



'I'he lilack horsefly* is very apt to place its large mass of 

 ('g-.2,s, contain in-g ui)wards of 500. in a certain position on a par- 

 ticular species of sedgv in low ground near swamps and ponds. 



The rather small horsefly known as Chrysops callidus ar- 

 langes her eggs in a single layei' on leaves of various kinds of 

 plants overhanging the water of ponds and small lakes. 



Chrysops moerens oviposits much like the last, except that 

 tii<^ eggs are placed over deeper watci'. It is not rare to find' 



Vw,. '.\. — Ekrs of an earllv. ('Iuijsiiiin uiorrcns, eularged. 

 (After Hart, P.iill. Ills. State Lab.. Volume IV.) 



tlit'se eggs on giant sedges standing in four or five feet of water. 



The eggs when first laid are white in the case of all species- 

 t!ms far observed, hut gradually get darker until they become 

 brown or black. The eggs of the various species of Chrysops 

 are usually shining black, while those of Tabanus are more often 

 clear brown. Thus we see that since the ,eggs of horseflies are 

 laid on a green surface they form a striking contrast with their 

 surroundings. 



Tt is well know II that in some of the flesh-flies or scavengers, 

 the eggs are either hatched, or nearly reach^ to hatch, when 

 deposition takes place. Not so with eggs of the horseflies, for 

 these do not show any a[)part'nt development when fii'st laid; and 

 ;is about seven days are required for them to hatcli under fa- 

 vorable conditions, we are safe in concluding that incubation 

 has tiot advaneed far at the time of laj'ing. It is very interest- 

 irg to watch a lu'ood of these minute larvae leave the eggs, for 



'Tabanu.t utmtiix. 



