(52 • [March, 



indicating that breeding was continuous and that the generations over- 

 lapped. The adults could frequently be seen hovering over the honey- 

 dewed leaves, and on two occasions in the laboratory were observed 

 feeding on the honey-dew, though they could not be induced to take a 

 sugar solution offered them. Flies confined in breeding cages paired in 

 the evening and the females commenced egg-laying two days after 

 emerging from their pupal cases. Oviposition lasted two days and 

 the females then died. Possibly under natural conditions the flies live 

 longer. 



When engaged in ovipositing the female Leucopis hovers over the 

 aphid-infested leaves as does a female sj'rphid. The eggs are deposited 

 siuglj^ on the leaves, close to the colonies of aphides and are attached in 

 a horizontal position to the surface of the leaf. When on dura leaves 

 they were invariably found on the underside of the leaf, but on cotton 

 leaves were seen only on the upperside. They may readily be dis- 

 tinguished from tlie eggs of Syrjylnis aecjyptius, with which they occur, 

 by their small size; they are barely visible to the naked eye, while the 

 syrphid ^^^ is 1 mm. in length. The eggs ©f the coccinellids are also 

 comparatively large, and are moreover arranged in a vertical position on 

 the leaf. From breeding experiments, it was found that the average 

 number of eggs laid by one fly was 34 ; possibly a number considerably 

 in excess of this would be produced by flies being under natural 

 conditions. 



The larvai occur among the aphides on which they feed. Their 

 method of progression resembles that of a geometer cater^iillar, and may 

 be described as follows : — The insect grasps the surface of the leaf 

 ajjpai-ently with its mo\ith and then, arching its bod}'', brings its pos- 

 terior end close to its head. Attaching itself by its anal prolegs it 

 releases its head-end and extends itself to take fresh hold with its mouth. 

 When feeding the larva seizes either the leg or body of an aphis by 

 means of its mandibles and sucks the body-juices. When once a hold 

 upon an aphis has been obtained it is rarely, if ever, released until 

 the unfortunate creature has been sucked dry. The emjDty aphid skins 

 are left attached to the leaf. 



Under laboratory conditions the life-cycle from egg to adult was 

 completed in eleven days, the various stages being as follows :— egg- 

 stage, 2 days ; larval stage, 5 days ; pupal stage, 4 days. The entire 

 life-cycle may be considered as being thirteen days, for, as noted above, 

 the adult female commences egg-laying two days after emergence. The 

 larva was observed to moult only twice during its five days of develop- 

 ment. When ready to moult it attaches itself to the leaf, a longitudinal 



