170 



each side near the lateral margin supplies an indication of metameric 

 division. Just in front of the foremost pair of punctures the larva 

 is encircled by a narrow groove, with which is connected a 

 longitudinal groove, which runs along each side and crosses the oral 

 depression. These grooves mark the limits of the cap, that in the 

 puparium splits off to permit the escape of the imago. On the dorsal 

 surface there is a pair of somewhat transversely elongate depressions 

 or punctures about midway between the encircling groove and the 

 oral depression. On the ventral surface, immediately in front of the 

 black cap, the anus may be seen in the shape of a small, dark, median 

 pore. The posterior stigmata are situate in the centre of the black 

 cap. In the case of a dead and dried female containing an adult or 

 a nearly adult larva, which appears to occupy the whole of the 

 distended abdomen, the black cap of the larva can be seen at the 

 hinder extremity of the abdomen, within the gaping orifice of the 

 vagina. After the larva is extruded the black cap speedily becomes 

 almost obliterated by the general chitinisation of the integument 

 to form the puparium or pupa-case, which is of a clove-brown or 

 nearly black colour, and closely resembles the ripe seed of a 

 leguminous plant. The imago subsequently makes its escape from 

 the puparium by splitting off the above-mentioned cap at the 

 cephalic pole. Notes on the larva and puparium of H. maculata, 

 Leach, and on the puparium of H. rufipes, von Olfers, will be 

 found on pp. 175, 176, and 178. 



The extrusion of Hippobosca larvae under natural conditions has 

 not been observed,* so that it is at present impossible to say whether 

 it takes place on the host, or whether the parturient females leave 

 the latter and alight for the purpose on some suitable spot on the 

 ground. It is obvious that if the larva be simply dropped while the 

 fly clings to the host, it must be exposed to the risk of being trodden 

 under foot by the latter or otherwise destroyed. The National 

 Collection contains two puparia of H. camelina, Leach, which were 



* When pregnant females belonging to this genus and containing immature larva; 

 are captured alive, they frequently abort, as do Tsetse-flies under similar conditions ; 

 the larvae deposited in this way are, of course, incapable of further development 

 or of turning into pupae. 



