I have successfully raised amaryllis in the ground in zone 9b. They bloomed in spring of 2018 abut over the summer they put out very few leaves. In the fall I pulled some and found thick basal plates, few roots, and it looked like something had been eating the bulbs layer by lay. The soil around the bulbs had not been disturbed. Any suggestions as to the cause?

Hmmm - does not look good to me, but not sure if that is disease or bugs.
@bsharf??

In any event, if it were me, I would rinse off that bulb thoroughly, and then remove any parts that are soft or rotten - it does not actually look rotten to me though. And then I would soak it in a water/peroxide mix for about 15 minutes, then set it on your counter for a couple of days (upside down if possible for the layers to drain) before planting it again - in sterile soil.

I managed to capture the culprit, an orangish worm about 1" long. Wonder if some type of drench insecticide would keep me from having to dig up all the bulbs.

I don't know what kind of insect you have, but frankly I think you are fighting a losing battle trying to save these bulbs. That red stuff is rot. Sometimes planting in the ground can be an issue in Florida, For ten years I attempted to put them in ground, and finally gave up. I was buying expensive bulbs that deteriorated within a few years. That's why I went to only planting Amaryllis in sterile soil in big pots. The. pots, are resting on brick pavers, so they drain well. I dealt with too much moisture, too much disease, and too many bugs, grubs and larva. I just did a quick internet search about insect pests of Amaryllis. Most of the bulb grubs, etc. eat out the inside of the bulb. The entrance wound is the access point for disease. There are systemic insecticides/ fungicides that I occasionally use, they are marketed for Roses. I question their effectiveness on advanced problems.

@bsharf
@hbv2020

I have similar climat to Florida (maybe somewhat cooler at winter, and no hurricanes, ב''ה), but same problems with most of the bulbs. All of them planted in pots, ground is changed every few years.

We have here a main nursery, that produce all the flower bulbs that are sold here, They plat it in the ground ,that separated with barriers from outside, and too much pesticides are use in the barrier and in the ground too.