they can also be black. i work at a petstore and when our shipment came in the frill had 30-40 black mites crawling all over him. he was lethargic and sick. when we gave him some veggies and forcefed some mealworms.. he started acting imslef... and then the mites were treated and he is wonderfull now. he has some issues with bite marks and scabs but is getting better!