46 NOTES ON MELANOSTOMA (dIPTERA; SYRPHIDAE) 



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occurred five days after hatching. One larva during its two 

 final instars was supplied with rose aphids Myzus rosarum and 

 Rhopalosiphuiii nervatum (instars iii and iv). It consumed a 

 total of two hundred and seventy-eight aphids in fifteen days. A 

 second supplied with the same aphids (instars iii, iv, v) con- 

 sumed two hundred and eighty-two aphids in seventeen days. A 

 third supplied with oak aphids Myzocallis bellus Walsh and M. 

 alhamhra Davidson (instars i to iv) consumed three hundred 

 and forty-six aphids in thirteen days. The fourth larva which 

 failed to pupate was supplied with similar aphids and consumed 

 two hundred and nineteen in twenty -five days. xVlthough the cast- 

 ing of the second molt was not observed, it ai)pearcd, from the 

 rate of feeding of the larvae, that this skin was cast three or 

 four days after the first molt had taken place. There is always 

 a notalile increase in the number of aphids eaten immediately 

 following a molt of the syrphid larva. During the last three 

 days of the larval stage few aphids were eaten. 



After the first molt the larva is light green, on the medio- 

 dorsum a white interrupted longitudinal stripe occurs. The 

 Cauda is truncate, the body inconspicuously armed with short 

 pale hairs and wrinkled transversely. The dorsal stripe is 

 doubl}^ interrupted so as to leave a diamond-shaped whitish spot. 

 Toward the end of the second instar the general color turns 

 brown and the median stripe fades. 



In th(i third instar the color is light blown. The whitish 

 dorsal stripe is In-oken up to form a series of diamond-shaped 

 spots. The vestiture is scanty and short. 



The full grown larva is aljout 10 mm. long and 2 nnn. wide. 

 The ground color is light brown. On each side is a narrow 

 longitudinal dull wliiU; stri])e and down tlu; medio-dorsum is 

 an interru])tcd whitish stripe, the interruptions ctiusing the 

 fonnatiou of three diamond sliai)ed spots. The body is trans- 

 versely wrinkled and laterally ("arinate. The vestiture^ consists 

 of scanty short pale hairs. The posterior respiratory lubes 

 are light brown, fused c'xce])t at their a]Hces; each tube as broad 

 at the base as it is long. The spiracular plates are remote, 

 dark brown, each bearing three straight slit-like spiracles. 



Th(; pupariuu) measures 5.8 mm. x 2.7 nnn. X 2.4 nmi., light 

 bi'own in coloi-, ])al("r on doi'sum and sides; dorsum arcuate, more 



