A Comparison of the Larvae of Eumerus strigatus, Fln., and Eumerus tuberculatus, Rond. (Syrphidae)

Abstract

Some years ago the writer published an account of the bionomics of the two species of Eumerus whose larvae attack narcissus and other plants. In this account it was pointed out that E. tuberculatus, first recognised as occurring in Britain by Collin in 1920, was far more abundant than E. strigatus, which had been described by Verrall in 1901. This finding was entirely contrary to expectation and threw serious doubt upon the accuracy of many previous records of injury to plants in which strigatus was invariably cited as the culprit. At the same time it explained in a large measure the absence of reports of Eumerus attacking onions in Britain, for in those countries in which damage to onions is of common occurrence the predominant species appears to be strigatus. In view of the foregoing, and of the fact that the successful cultivation of onions is exceedingly difficult and at times impossible in regions where attacks by Eumerus are experienced, it is desirable that further information be obtained as to the occurrence of strigatus in Britain.