Handle the bird so she stays calm
A parasite check done on a flapping, frightened hen finds nothing. Pick the bird up quietly, tuck her body against yours with one hand supporting her breast and her wings held gently against her sides, and let her settle before you start. Work in good daylight, because the parasites you are looking for are a millimetre or two long and the colour of dust or dried blood. Hens who are handled regularly for checks protest far less, so make this part of ordinary handling rather than an occasional emergency capture in the run.
Part the feathers where parasites cluster
Bird lice live their whole lives on the hen, and they gather where she cannot easily reach: the fluffy feathers around the vent, under the wings, and around the base of the neck and head. Push the feathers back against their natural lie with your fingertips so you can see skin and feather bases. Lice show as pale, straw-coloured specks that move away from the light when disturbed. Their eggs are the surer sign: clusters of whitish, gritty lumps cemented firmly to the feather shafts close to the skin, especially in the vent fluff. A hen carrying a heavy load often has dirty, broken-looking feathers around the vent and skin that looks sore and thickened.
Know which enemy you are looking at
Feather lice feed on skin debris and feather material, so they are found on the bird at any hour. Red mites are different: they hide in the cracks of the coop and perch ends during the day and climb onto the birds to feed at night, so a daytime handling check can miss them entirely. If hens look pale, restless or off lay but the feathers look clean, inspect the coop instead, running a fingertip along the underside of perches and into corners; a smear of grey or red specks gives them away. Check legs during handling too. Raised, crusty, lifting scales on the legs and feet point to scaly leg mite, which burrows under the scales rather than living in the feathers.
Record it bird by bird
Work through the flock systematically and note which individuals carry eggs or live parasites and which are clean, because treatment and rechecking are aimed at the affected birds and the coop as a whole. A bird crawling with lice today and clean next week tells you your coop cleaning and dust-bathing provision are working; a bird who is always the loaded one may be a bird who is not dust bathing, perhaps because she is low in the pecking order or unwell in some other way. Writing the findings down per bird turns a vague worry about the flock into a short list you can act on.
What to do with what you find
A light finding calls for diligence rather than panic: deep-clean the coop, renew bedding, make sure the dust-bathing area is dry and inviting, and recheck the affected birds within the week. If birds are losing condition, if combs look pale and hens stop laying, or if numbers climb despite cleaning, talk to a poultry vet or an experienced poultry supplier about the treatment options suited to laying hens, and follow label directions exactly rather than improvising. On KinsLe, scheduling the handling check as a recurring Care Teams chore means one named person works through the flock each week and marks the inspection complete, so no bird goes unexamined for months at a time.