156 MAINE AGRICULTURAL EXPERIMENT STATION. 1917. 



next hour. She died over night without any further oviposition ; 

 but the few eggs were sufficient to establish the identity of the 

 unusual larvae. These eggs hatched in the laboratory between 

 8 A. M. August 28 and 8 A. M. August 29, and speedily developed 

 into larvae of the characteristic appearance. 



The first puparium was formed August 24 in moist earth 

 in the bottom of the jar confining larvae collected August 7 from 

 willow ; two others August 27 and two others August 29. 



The first adult (from a puparium formed August 27) was 

 disclosed Sept. 12; the others during shipment from Maine to 

 Ohio between . Sept. 13 and 20, the exact date not determined ; 

 except for one specimen which yielded a parasite (species unde- 

 termined) some days later. 



Noting the voraciousness of the young larvae of this species 

 the following tests were made of their capacity for destroying 

 aphids : 



Sept. 7, 9.30 A. M., three larvae were enclosed with 150 

 aphids of Pterocomma smithiae. At 8 A. M., Sept. 8, not a single 

 whole aphid, living or dead, was found in the vial, nothing 

 but the cast-off skins. In other words each of the three larvae 

 had devoured, on the average, 50 aphids in 22^ hours. At 11.40 

 A. M. of the same day the same three larvae were enclosed with 

 175 aphids of the same species, some of them actively reproduc- 

 ing. At 5 P. M. many of the aphids were still living, but by 8 

 A. M., Sept. 9, all had been devoured, most of the feeding in 

 this case having taken place at night. 



On August 31, another female was captured in the field 

 about the infested willow but was slightly injured and died before 

 ovipositing. 



On Sept. 1, several full-sized larvae were found under loose 

 pieces of dead bark on the infested willow trees, presumably 

 seeking a site for pupation and possibly for hibernation. The 

 larvae taken into confinement however died without pupating. 



On my return to Orono, June 7, 1917, an examination of the 

 trees, infested the previous season disclosed four puparia, three 

 of them glued to loose pieces of bark on the trunk or principle 

 branches of the tree, the other on the ground among fallen pieces 

 of bark. 1 



*It may be noted that the puparium found on the ground is the only 

 o:ie of the lot which failed to yield either a living fly or parasites; this 

 (a male) d : ed without emer^'roT. 



