Is the culprit? Or this? Both are pictures of armyworms. You don't want them on your plants, as you've discovered. Bt will dispatch them quickly and thoroughly if that's what they are.

If it makes you feel better, I have never seen so many onion root maggots in garlic -- usually it's more like two heads out of a hundred, or none. This year two out of five heads of small hardnecks were ruined. These grew near one another. It is possible that there was a "lens" of damage when flies laid eggs in a small area. Some silverskins in another bed had zero damage. Any opionions on whether it was location or variety that protected the silverskins? In the link below, you can click to enlarge the photo with the root maggots in it. Here is a link that might be useful: photo of onion root maggots on garlic

Wow lots of interesting stuff here! I think there are multiple issues here, and, since the health of the plants isn't great, I would deal with all possible problems rather than hunt down one specific one. If it were me I would do the following, since doing them would fix any of the most likely problems that you may be having. I would change the mix to a free draining one. I would check the roots, and pot into a container that is only a little larger than the rootball. I would put them in a partially sunny position after the repot until they get used to their new mix and pot. I would then move to a sunny location once things started to settle. I would make sure the room had plenty of humidity with gravel trays or a humidity. I would make sure the room was warm, and provide bottom heat to the pots if possible. I would inspect for bugs. Mites and scale seem the most prolific - possibly mites in your case. Webbing is a telltale sign, and sometimes hard to spot, but not always present. I would treat with Toni's spray regardless (she can tell you the ingredients, or you can search previous posts.) If you do spot bugs, use Toni's spray or a suitable one for fruiting plants from a garden centre. I would water these (after the repot) only when the new medium was closer to dry than damp. In a new medium you won't have to worry so much over watering - if it is the right medium it is unlikely you will overwater unless you go nuts with it. Fertilize only very lightly until the tree is back to health, then feed with a high nitrogen feed every couple of weeks. Citrus bounce back, but they take time. These are not by any means the be all and end all of things you should do, they are merely what I personally would do :) Danny

Research fruitworm and pepper weevil. Good luck. Kevin