onion maggots

I recently brought in my herbs from the garden and planted them in a cedar planter box under our living room window.  My rosemary was too dead to bring in, but my thyme and chives are doing alright after a week or so, or so I thought until today.

I was grooming my chives by pulling away dead leaves when I accidentally brought up a bunch of live ones.  After doing so, I noticed that the base looked a little bit like the green onions you buy at the store with stubby white roots, and thought Huh. I didn't know that.  And then the roots started moving.  For a moment I thought I was hallucinating, but quickly realized that there was something living in my chives and it looked like maggots.

After inspecting and disposing of the chive saboteurs that I had uprooted, I went to the internet to identify them as onion maggots.  My current approach is going to be keeping the chives warm and dry, but I'm curious to hear if other people have more direct remedies for this pest.

Worst case, my chives die off and I start new ones; they're easy to grow, so I won't be heartbroken.  If something like this happened to my beautiful little thyme plant, however, I would be very agitated.