The larval stages of two species of Syrphid flies, namely, Eumerus tuberculatus and E. strigatus, are frequently found in rotting narcissus bulbs, in iris and tulip, and in vegetable roots, such as parsnip. The writer has shown that frequently the decay, at least in the narcissus, is directly attributable to the presence of these larvae and that they must therefore be considered to be primary pests. It was further shown that, contrary to current opinion, the predominant species at the time of writing was E. tuberculatus. In passing it may be recorded that this predominance has, in each subsequent year, become more marked, until at the present time E. strigatus has ceased to rank as a bulb pest, at least in South-West England, Holland, and probably the Irish Free State. The larvae of the two species are very similar to one another, and it has not been found possible to separate the species, with any great degree of accuracy, during the immature stages. In the adult form, as shown by Collin, separation is easily effected. In the course of experimental work with these flies a third, and superficially somewhat similar Syrphid, namely Syritta pipiens, L., was frequently bred from decayed narcissus bulbs.