Insects and Parasitic Diseases. ]05 



Young female Louse-flies are capable of copulating five days after 

 their emergence from the pupae, but when a few insects only are 

 liberated on, and allowed access to all parts of, the host, the period 

 is usually longer, owing to the chances of early mating being les- 

 sened. Under these conditions mating has been found to take place 

 on the sixth to fourteenth day. 



The young female extrudes the first pupa in a minimum period 

 of thirteen days after her emergence from the pupa. The usual 

 period, however, is longer, i.e., up to twenty-three days. 



It has not yet been found possible to determine here the length of 

 life of, and the number of pupae extruded by an individual female 

 Louse-fly. No positive i-esults therefore can be given as to the 

 average period elapsing between the extrusion of each pupa during 

 the whole life of an individual Louse-fly under the conditions of 

 these investigations except that it would appear that pupae may 

 be extruded, for a time at least, at an average rate of one every 

 nine days. 



The period of viability of the Sheep Louse-fly when removed from 

 the host and kept without food is longer under Southern Australian 

 -^'onditions than has been recognised elsewhere. European and 

 American authors and investigators, whose works are available here 

 for reference, are agreed that the Sheep Louse-fly does not live to the 

 eighth day, and that most of them die in from two to four days. 

 Sweet and Seddon showed that these insects could be kept alive off 

 the host in Victoria for eleven and three-quarter days under cool 

 uniform conditions in early summer. The present writer's investi- 

 gations show that even this latter period may be exceeded, as was 

 the case in no less than ten of the forty-six groups of Louse-flies 

 •experimented with. 



The adult Louse-fly lives longer apart from the host than does 

 either the unfed insect under one day old or the young insect of 

 three to seven days old which has fed upon the host. The female in 

 ■nearly all cases outlives the male. 



The longest period for which an adult female has been kept off 

 the ho>st and without food is up to the eighteenth day. This " tick " 

 was kept in a dish of sheep-pen sw;eepings, containing portion of a 

 tree-trunk, in a dry, well-ventilated cellar, where the temperature 

 was very uniform in contrast to extremes above and below in out- 

 side temperatures. 



Under similar conditions groups of Louse-flies under one day old 

 (unfed) and from three to seven days old (fed) all died in fourteen 



