Narcissus bulb fly

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.