F Onion - Growing tips
Potential pests: Onion maggots
Onion maggots are larvae of the gray fly. They are small, cream / white coloured maggots that infest the bulbs of onions, leeks, garlic & turnips (possibly other root vegetables as well), causing tunnels. The maggots have about 3 generations each year. The first generation is the largest and causes the most damage.
Onion maggots overwinter in the soil in the pupae stage. The first few years I was gardening I kept finding these in the late spring when I was preparing my soil for planting.
The first sign of an infected plant, based on my experience, is that the onion tops fall over. This year I planted onions in a plot that did not previously contain onions and only about 1/3 of my crop was affected. See the link above for some tips on how to potentially evade the pesky onion maggot, if you are considering growing onions in the community garden.