Lice are the most common ectoparasite found in backyard and free-range flocks worldwide. They are small, flat, wingless six-legged parasites which are host-specific. Lice spend their entire life cycle on the chicken. During this time, they survive by eating feather parts, dead skin and blood. Chickens are normally relatively effective at keeping lice and other ectoparasites off of their bodies. They accomplish this through dustbathing and preening (grooming) their feathers daily. However, without an appropriate area to dustbathe and/or reduced ability to preen (such as birds with beak deformities
, those with trimmed or injured beaks, and injured or sick birds), lice infestations are more likely to become an issue. Molting also greatly reduces louse populations. Molted feathers should be promptly removed.
Signs of Lice
Although there are certain behaviors which may raise suspicion of an ectoparasite problem in the flock, you won't really know until you give each chicken a health exam. Conduct the examination somewhere with good lighting. Outside in direct sunlight is ideal.
While examining the bird, start at the area just above their vent. Part through the feathers to expose the skin. Adult lice are large enough to be visible to the naked eye, but can sometimes be difficult to see depending on the color contrast to the bird's feathers and skin. However, when adult lice are exposed to light they will scatter and hide. Their rapid movement will catch your eye. In severe cases, clumps of cement-like clusters (of lice eggs) will be attached to the base of the bird's feathers.
Common Types of Poultry Lice
There are several different species of lice which are found on chickens. They differ in body shape, color, and size. Each species has certain locations they prefer to inhabit on the chicken's body.
- Chicken Head Louse: As adults, Cuclotogaster heterographus are 2.5 mm long with oblong grayish bodies and triangular heads. They tend to live on the base of the feathers of the bird's head and neck.
- Fluff Louse: As adults, Goniocotes gallinae are 1.5 mm long with round, yellow bodies. They are found within the feather fluff along the bird's back, abdomen, and vent. Eggs are found in clusters near the base of feathers.
- Brown Chicken Louse: As adults, Goniodes dissimilis are 3.5 mm long with reddish brown bodies. They can be found throughout the chicken's body and live on the skin and feathers. Eggs are found in clusters near the base of feathers.
- Wing Louse: As adults, Lipeurus caponis are 2 m long with slender, grayish bodies. They are typically found on the bird's skin and undersides of the large wing and tail feathers. Eggs are found in clusters near the base of feathers.
- Chicken Body Louse: Menacanthus stramineus are one of the most common species of poultry lice found in backyard and free-range chickens worldwide. They are 3.5 mm long with yellow to brown colored bodies. This species live close to the skin and found around the bird's vent, breast, head, and underneath the wings. Eggs are found as cemented clusters along the base of feathers.
- Shaft Louse: Menopon gallinae are commonly found in backyard and free-range flocks worldwide. They are 2.3 mm long with pale yellow bodies. They live on the shafts of newly grown feathers along the bird's breast and thigh areas. Eggs are found cemented individually at the base of feather shafts or along feather barbs.
Lice have a life span of about a month. During that time, one female louse will lay from 50 to 300 eggs (referred to as "nits"). Lice eggs look like whitish, oval capsules which are cemented in clusters or individually to the base or barbs of the feathers. The eggs are often easier to find then the lice, since the eggs will glisten in reflected light, particularly before they hatch. Most lice eggs require 4 to 7 days to hatch and then 10 to 15 days to reach adulthood. Hatched eggs will remain attached to the feathers and appear grayish and flattened in appearance.
Not all members of the flock will necessarily have lice. However, the presence of some lice on most birds or of egg clusters attached to one or more birds is enough cause to assume that the entire flock has lice. Treatment involves removal of the eggs (if present) and application of an insecticide. Removal of the eggs is important because they are resistant to insecticides. It can be made easier by soaking the bird in a bath first, or by coating them with a softening agent such as NuStock or similar product. There are many commercial insecticide products available on the market for treatment of lice. However, just make sure to read the product label to ensure that it specifically states it's effectiveness against lice (as there are some products intended for mites and fleas only, and not effective for lice).