Symptoms

The main symptom is center of bulbs are hollowed out and the flower bud is destroyed. Many infested bulbs rot away although some survive to send up a few scrawny grasslike blades the following year.

Spot them

The adult flies are 9 to 12 mm long and resemble bumble bees, although some are more reddish brown, orange, or tan. Unlike bumble bees, narcissus bulb flies have a very rapid flight and also tend to hover in flight. Newly hatched maggots are about I mm long. Third stage maggots are about 19 mm long and are a dirty tan colour. The maggot is plump and slightly arched, and the skin is tough and wrinkled. The mouth hooks and breathing tube are almost black.