In the research of voracity of syrphid larvae it was found that the number of aphids Aphis Jabae Scop. eaten by larvae oscillated between 300-800 specimens depending on the syrphid species. Larvae of Syrphus ribesii (L.) appearred to be the most voracious. It was found that predator-prey ratio from 1:25 to 1:50 was the most effective at Episyrphus ba/teat us (Deg.) and Sphaerophoria scripta (L.) larvae in Aphis fabae control on broad bean.