First of all, it should be noted that you won't find narcissus flies in the average household.
Characteristic of the large narcissus fly is that the damage caused is not clearly visible from the outside.
The larvae of narcissus flies, which resemble maggots, commonly affect narcissus and hyacinth bulbs.
If it is narcissus fly attack, the bulb will be slimy and these should be thrown away.
Hoe regularly around the plants to kill any larvae, and to make sure there are no large cracks in the soil around the bulbs down which the adult narcissus flies can crawl.