Observations on the Life History, Harits and Control of the Narcissus Bulb Fly Merodon Equestris Fab., in Oregon

Abstract

The Narcissus Bulb Fly, Merodon Equestris Fab., has been introduced into Oregon from Europe and has established itself in the commercial plantings of Narcissus. In one planting 14 per cent of the bulbs were destroyed by this pest. Our observations to date show the seasonal history of this pest to be as follows: Winter is passed as full grown larvae in the bulbs. In March and the early part of April the larvae leave the bulbs usually through the neck and pupate in the soil, about y. inch deep. The flies emerge mainly in April, but can be found in the fields until in June. Egg laying takes place in the latter part of April and in May. The majority of the eggs hatch in from 8 to 10 days and the young larvae enter the bulb usually through the basal plate. The larvae are full grown by September. The injury by this insect is characteristic. The center of the bulb is eaten out and partly filled with brown excrement. Infested bulbs are not easily detected, and may be as hard and solid as uninfected bulbs. All larvae in the bulbs can be killed by the Hot Water Treatment as applied for the Stem Nematode, Tylenchus dipaci Kuehn his treatment is not a cure-all, however, as it is impossible to remove all the bulbs from the soil when digging. Tests with ovicides made in the spring of 1926 were promising; 100 per cent control was obtained with corrosive sublimate.