The present investigation was carried out on in vitro mass multiplication, larval feeding capacity, and pollination efficiency of two aphidophagous syrphids viz., Eupeodes frequens (Matsmura) and Episyrphus balteatus (De Geer) (Diptera: Syrphidae) on cabbage aphid (Brevicoryne brassicae L.) (Homoptera: Aphididae) on mustard crop under mid hill conditions. The results revealed that the incubation, larval, and pupal periods were 3.5, 12.4, and 11.9 days, respectively for E. frequens and 3.8, 13.7, and 8.8 days, for E. balteatus. Longevity of male and female was 15.2 and 17.6 days for E. frequens and 10.6 and 12.6 days for E. balteatus, respectively. When the adults were fed on different diets, adult longevity and fecundity recorded significantly maximum on 10% honey solution + fresh pollen grains. E. frequens consumed an average of 261.7 individuals of cabbage aphids per larva during total larval period, whereas the larva of E. balteatus consumed 393.6 cabbage aphids. The pollination efficiency of hoverflies on Indian mustard (Brassica juncea L.) was studied under caged conditions. It was observed that the plants pollinated by E. balteatus and E. frequens showed 55.12 and 52.97% seed set. Among the different diets, fresh pollen grains + 10% honey solutions recorded to be the best diet for mass rearing of syrphids.