146 THE EARLY STAGES OF TABANID^ 



The eggs were laid in a compact mass either extended on a flat 

 surface or surrounding various attached objects, usually of small 

 diameter, such as projecting splinters of wood, suspended fibers of 

 jute sacking, fine brass wire, a single animal hair, and coarse iron 

 wire. Upon these materials the eggs were laid in an ellipsoidal 

 form sometimes surrounding the objects completely or nearly so. 

 On one occasion two egg masses were found upon a small splinter of 

 wood which they entirely enveloped. The surfaces of the egg masses 

 were continuous, so that the double mass resembled a single large 

 one. When eggs were found deposited on a flat surface, on two occa- 

 sions a leaf was the object selected. These were leaves of an orna- 

 mental plant which was used for shade purposes in the breeding cage. 

 The plant grew close to the cement water tank in the breedmg cage. 

 In all other instances the eggs were deposited upon woodwork on the 

 sides and ceihng of the cage, invariably upon the shaded portions, as 

 the under side of beams and partitions. In egg laying upon flat sur- 

 faces there was a strikingly constant geometric form. Usually the 

 form assumed was roughly a pentagon with a biconvex center. 



At the beginning of oviposition (Plate 2, Fig. 24) usually two eggs 

 are deposited in the position of an inverted V. Three to four eggs are 

 then laid on either side of the apex of this V, and then one side and 

 then the other is built up, rather irregularly at first, until the sides 

 of the pentagon are completed. The eggs are laid cleanly and defi- 

 nitely, each line slightly overlapping the preceding one. When the 

 eggs are laid in the extended order, they are deposited three or four 

 layers in depth, but usually as many as six layers are required to 

 complete the mass when the eggs surround a convex object. 



In the process of laying, "the body is held away from the egg mass, 

 the legs being planted firmly." When the eggs are attached to one 

 of the objects mentioned above, the insect stands with head down- 

 wards, the fore legs suspended alongside the head, the hind and middle 

 legs supporting the weight of the body. At the first movement, the 

 anal end of the body is bent towards the thorax under the abdomen, 

 and with a Siight jerk the egg is laid, while the brush-like appendage 

 of the ovipositor exudes a tiny drop of liquid coating the egg as it is 

 deposited. The movement of deposition is very much like squeezing 

 a bit of pasty material from a collapsible metal tube. 



