Horde of small ticks with 8 legs
American Robins raised two broods of young on wires under our eaves, close to the window of my daughter's bedroom. After they left, my daughter had some red marks on her neck. We found two dozen tiny ticks on or near her bed and at least 200 more outside on the wall of the house. We looked closely at perhaps 50 and all were about 0.5 mm long and had 8 legs. If they had been newly hatched larvae, they should only have had 6 legs. But I can't understand how so many second stage nymphs could be together.
If anyone has an explanation, I would be most grateful.
Outside United States
These might be mites and not ticks. They are of the size you mentioned.
See the attached links for information on mites.