Ann, I think Dirt covered nearly all the tricks I know of regarding fighting this very difficult pest. Don't want to use poison myself either and even if I wanted, very few chemicals are allowed for the home gardener around here. Some claim that deeper planting (10 inches) will make it more difficult for the larva to reach the base of the bulb so could be worth trying. Growing early varieties, removing the foliage (they like the scent of the decaying foliage) and firming the soil around the base of the bulb could also be worth trying.
I don't grow many daffodils anymore... just a few survivors and I have some in pots. I try to cover most of the pots after bloom, but not all of them. I keep a few pots uncovered, placing them where it's nice, warm and a little sheltered... conditions which the narcissus bulb fly seem to like. My thinking is that by keeping at least a few narcissus bulbs easily available, perhaps I can get them to lay the majority of their eggs in these pots and then I can discard all infected bulbs later on
Apparently they can damage other bulbs as well, but I'm unsure to what extent and indeed I have read some differing stories regarding what species are at risk! In the UK they for instance have a lot of problems with snowdrops, but I haven't noticed that myself... however that certainly doesn't mean the problem isn't there
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This really is a very difficult pest to initially spot, unless one knows what to look for and judging by the responses in this thread, I wonder if it isn't much more common than what I have been led to believe. I think I both saw these flying around in the garden as well as actually snapping pictures of them several years before I understood what they were
