Insects and Parasitic Diseases. 103 



temperatures ranging from 64.4°F. to 82.4°F. The first young 

 Louse-fly emerged on the tenth day, and otliers followed until the 

 twenty-sixth day, when the last emerged. 



The next highest percentage of emergences was obtained in an 

 experiment in which th|e pupae were placed on dry sand in an 

 incubator at a uniform temperature of 71.6°F.; under these con- 

 ditions 82.6% of the pupae developed into Louse-flies, the first on 

 the third day and th.e last on the thirty-second day. 



The next most favourable condition for the development of the 

 pupae Avas a temperature of 93.2°F., and the substitution of moist 

 paper for dry sand. Under these conditions 75% of pupae less than 

 one day old when gathered from the host emerged on the eighteenth 

 and nineteenth days. A slightly lower percentage of emergence, 

 namely, 72%, was obtained when the pupae were kept in a covered 

 tin on the laboratory table, where the temperature ranged from 

 60°F. to 90°F. In tliis experiment the first Louse-fly emerged on 

 the first day and the last on the forty-second day. When the pupae 

 were kept on dry sand in the incubator at a temperature ranging 

 from 64.4°F. to 82.4 F., 60.6% of them developed into the imaginal 

 state — the first on the fourth day and the last on the twenty-first 

 day. On moist sheep-pen sweepings in an incubator, at tempera- 

 tures ranging from 78.8°F. to 86.9°F., 57% of the pupae experi- 

 mented with produced Louse-flies, the first of which emerged on the 

 twelfth day and the last on the twenty-first day; 42.8% of the pupae 

 which were incubated in a dry dish at 91.4°F. produced Louse- 

 flies, the first of which emerfged on the seventh and the last on the 

 eleventh day. The next most favourable condition for development 

 was in wool on a post out-of-doors, at a season of the year during- 

 which the temperature ranged from 47°F. to 84° F. ; 3L5% of the 

 pupae produced young Louse-flies, the first of which emerged on the 

 third day and the last on the twenty-seventh day. This r.esult, it 

 will be noticed, is of particular interest, inasmuch thnt the condi- 

 tions under which the experiment was carried out closely simulated 

 natural conditions. Only a very slightly lower percentage of 

 emergences, namely 31%, was obtained in an experiment in which 

 the pupae were placed on dry sheep-pen sweepings in an incubator 

 at a temperature of 71.6"F. Under these conditions the first pupa 

 developed into a young " tick " on the fourth day and the last on 

 the twenty-third day. 



In two experiments under almost natural conditions — namely, on 

 sand on the lawn — only 6% of the pupae developed. In one of the 



