yes that sounds right
it is feather mites or lice
they do take some getting rid of them
Here is a article by my friend Nathalie Ross who has used it a lot
Using Ivermectin is good here is the amt for Ivermectin pour on 5%
For the pour on Ivermectin (not Eprinex) the dosage I   
use is as follows:   
1 drop - OEGB sized small bantam female   
2 drops - OEGB sized small bantam male   
3 drops - average bantams   
4 drops - large bantams, small commercial fowl   
5 drops - most commercial fowl, small giant hens   
6 drops - giant breeds of chicken   
  
I always use a 3 cc syringe that I just fill to about 2 cc's with a 20 gauge needle.  The needle WON'T be injected into the chicken, but does make it easier to dispense a controlled correct sized drop.  It also is easier to get in there between the feathers.   
  
For location, you'll want to find an easy to reach   
spot with as little fluff as possible. I've had the   
best luck with the back of the neck when I am by myself.  I just pick up the chicken in my left    
hand, ruffle around the feathers with my right hand until I find a nice clear spot, then rotate the syringe around to dispense the drops exactly on the skin.   
  
If you hit the fluff, it will soak in before    
you can do anything and will be wasted.  That stuff soaks in like lightening (which I discovered to my horror when I accidently got about 1 cc of it on me from the bottle - I'm worm free 
GLH added
when trying to get rid of lice and mites the building needs cleaned also you can do this
CLEAN THE CHICKEN HOUSE AND   
then you need to get the mites and lice  where they live    
take a gallon can and put 1 pt of cooking oil and 1 pint of keroseen and paint the roost poles    
and all the cracks in the wood of the building    
especially the knot holes if any are in the wood    
these areas are where the mites and lice live and breed    
then I would clean out the bedding and start fresh by putting    
a good layer of sevin 5% on the bare floor now put the new bedding back in the building    
this will get rid of the mitesand lice and any lice living in the building    
always do this so you can leave a window cracked that night    
so fumes will escape    
ALSO FEED THE BIRDS THIS   
besure to feed the birds affected the    
natural probiotic wet mash   
each bird   
3 tbsp of dry crumbles   
5-1/2 tbsp of milk any kind   
1 tbsp of yoguart   
mix and feed twie a day till the bird is healed then once a week for life 
you have to multiply the number of birds being given this wet mash probiotic as this is for one bird
It helps the birds gut flora to come back stronger after the delousing medication 
PM me for any other problems