236 THE CANADIAN ENTOMOLOGIST 



brassiccB L., Myztis persicce Sulzer and Macrosiphum pisi Kalt. colonies were 

 searched frequently, but in vain, for larvae and pupae of the syrphid. 



Stages and Parasitism. 



At El Centro 8 ova oi fracta deposited March 22nd hatched 4 in two, 4 in 

 three days, and two resultant larvae pupated after a stage of 11 and 12 days; 

 one individual emerged as an adult fly 8 days after it pupated. Six other 

 individuals varied in the pupal stage from 5 to 12 days in April.' From March 

 22 to April 30 the minimum daily temperatures ranged from 50 to 63 F., and 

 the maximum from 71 to 96 F.; the average daily minimum was 58 F., and the 

 average daily maximum 86 F. 



Between the middle of February and the end of April 45 large larva^ and 

 pupae of Allograpta were collected in the field; of these 12 died in the pupal 

 stage, 14 yielded mature A. fracta, 1 yielded mature obliqua, and 18 yielded 

 parasites. From two of the parasitized puparia several imagoes of Pachyneuron 

 issued, and from the other 16 puparia single Ichneumonid adults emerged. 

 Most of the latter were Eiplazon laetatoriiis Fabr., adults of which were com- 

 monly observed flying about the fields. The puparia of the parasitized flies 

 turned brown almost immediately after pupation. Within the puparia the 

 I^arasites developed a little more slowly than the hosts. 



DESCRIPTIONS 



The egg is white, microscopically sculptured, elongate oval, in length about 

 .85 mm.; in diameter about .25 mm.; deposited by the parent beside a colony 

 of aphids. Eggs observed on barley plants were all placed so that their long 

 axis was aparallel to the long axis of the blade. 



At birth the larva is nearly cylindrical, widest at the middle, whitish in 

 colour, the mouth-parts gray. Each segment bears small, fleshy, conical eleva- 

 tions. The posterior respiratory tubes are short, not fused, and divergent; 

 they are whitish, tipped with light brown. The transverse folds of the bod}' 

 are faint. After feeding the colour of the larva during the first instar becomes 

 grayish white, the area about the dorsal vessel pink. 



After the first moult the larva measures about 4.5 mm. in length, and 1 

 mm. in breadth. The green colour which persists until the pupa is about to 

 give forth the imago is now obvious. Each of the fleshy conical elevations 

 of the integument is surmounted by a short pale bristle. The posterior respira- 

 tory tubes become lengthened, basally fused mesad, divergent at the apices, 

 twice as long as their combined basal width, pale green tipped with brown. 

 For a few days after the first moult the pink dorsal stripe is apparent, gradually 

 fading away. The fat bodies show through the integument as two narrow 

 whitish stripes running longitudinally one down either side of the narrow dark 

 dorsal vessel. 



The full-grown larva is 8 to 9 mm. in length, 2 mm. wide, and about 1.2 

 mm. in height; elongate oval, somewhat flattened on dorsum, the anterior end 

 drawn out to a point when the insect extends itself; integument finely papillose, 

 transversely wrinkled, the fleshy conical elevations surmounted with pale 

 spines, colour green, with two narrow whitish longitudinal stripes flanking the 

 dorsal vessel, posterior respiratory tubes fused mesad, .5 mm. long, the combined 

 base about 27 mm. wide. The structure of the stigmal plates is very similar to 



