In answer to you question. I don't know as I have not seen the hens, house or run. However you do sound as it you might be giving them a little too much attention and might not have diluted the concentrate by 90%. Except when things are 'wrong' I would more than halve the treatment regimes recommended by manufacturers. (This does not apply to the use of antibiotics when a full and complete doseage is necessary.)
If you can take the bird out of that house and let them roost outside or another house for a couple of days.
The Poultry Shield website gives the following information:
+ Revolutionary approach to controlling Red Mite in Poultry
+ Safeguard against Bird Flu
+ 96% red mite & lice killed in 48 hours including eggs
+ Effective against bacteria, virus, yeast and fungi
+ Environmentally friendly
+ Non-toxic
+ Use as a weak solution for cleaning feeding equipment
+ Can be used without removing the birds from the house, but DO NOT use directly on the birds.
Available in 1 litre and 5 litre sizes of concentrate, and 1 litre Ready to Use Spray bottles.
Poultry-Shield is a safe liquid concentrate, diluted before use, for spraying onto the Red Mite and their eggs. It is essential that Poultry-Shield actually makes contact with the mite and their eggs. The reaction on contact is the break up of the wax coating causing dehydration and death of the mite. Poultry-Shield at the same time penetrates the protective coating of the mite eggs producing a similar reaction. The kill time from contact of Poultry-Shield with the mite to eventual dehydration is approximately 48 hours.
Residual effect is the destruction of the mite eggs thus breaking the reproductive cycle. Unlike the powders, Poultry-Shield has a deep penetrating effect into the cracks, crevices and corners where the mite aggregate to sleep and lay eggs.
Bonuses are Poultry-Shield is a bactericide, a virucide and a fungicide. Poultry-Shield is a multi-purpose cleaner. We recommend regular cleaning of the Henhouse with this product to keep the danger of all infections at bay. Best applied with a Pressure Sprayer and using rubber gloves, which eases the job and makes it most effective or, on a small scale, with a used, rinsed kitchen cleaner spray bottle. In a 10% solution, this product is able to clean and remove the organic matter present on material, equipments, cages. It has excellent sanitising properties and will reduce cross contamination.