Bulb fly season has begun

Jane McGary janemcgary@earthlink.net
Mon, 26 Apr 2010 08:59:03 PDT
Boyce Tankersley wrote
>I fear we may have the pest [bulb fly] in Chicago as well. A fly like creature
>about the size of a bumble bee that hovered over the foliage and did not
>indicate any interest in visiting the flowers.

You can tell bulb fly, or narcissus fly as it is sometimes called, 
from other large hoverflies and similar bees by the sound it makes as 
it flies. This is a high-pitched whine such as one can imagine 
emanating from a giant mosquito.

The best protection for small groups of precious amaryllids (its 
predation is, as far as I know, limited to that family) is to cover 
them with a "floating row cover" such as Reemay, which will prevent 
the flies from landing on the foliage and depositing their eggs. In 
the garden I have also had success by just laying a covering of 
coarse sand and gravel over the prostrate, withering foliage of 
Sternbergia. Apparently these pests do not prey as much on plants 
grown in shade, so Galanthus and Narcissus in shade may be safer; I 
haven't lost any snowdrops to them except in the bulb frame, where I 
now cover the few that grow there.

People use various tactics to kill the bulb flies in the garden, such 
as smacking them with tennis rackets or blasting them with the 
long-range insecticide sprays used on wasps and hornets. When the 
adults emerge they can often be seen mating, a good time to kill them 
while they're distracted; they are very fast-moving otherwise. I have 
a lot of common daffodils in the sunny part of the garden, so I check 
that area when I notice any bulb flies and usually can kill quite a 
few of them.

Jane McGary
Northwestern Oregon, USA

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