Try this link:

 

 

 

I find the red mites hide in old wood and are difficult to see unless totally infested.

That was one of the first things I checked for with Major and if in a dark room using a flashlight they are easy to spot. I went in a couple of times in the night to look him over and check him out. 

They like to collect in breeder boxes and  usually most breeders use the Sevin Dust to keep them at bay and/or kill them off.

Too2

Hi Rose, Welcome.

My first comment is to not allow your tiel to breed. A bird who is ill with any disease is in too poor condition to breed and to help rear babies. Megabacteria is a very serious illness and he should be kept as quiet as possible without the stress related to breeding.

The link given by ZonkersMom has several articles about this fungus which will help you to understand the disease better.

I haven't had a chance to read the other links given but I feel sure they will say almost the same thing.

I do hope he gets well.

Annie