Poultry Lice

IRWIN H. ROBERTS AND C. L. SMITH.

LICE infest chickens, turkeys, ducks, geese, pigeons, and other birds.

Each class of poultry is parasitized by its own kind of lice. Ten species of lice are common on chickens. Six of them may be found anywhere in the United States. At least three occasionally cause serious losses. Because they are common and easy to see, lice probably get more attention from poultrymen than all other parasites.

Most commercial poultry operators manage to keep their establishments relatively uninfected, but the losses lice cause in small farm and barnyard flocks are great. The average annual loss to the whole poultry industry in 1942-1951 from all external parasites was estimated to be 80 million dollars. We can stop such losses; at small cost and with little effort, any flock can be kept practically free of lice.

Poultry lice seldom are more than three-sixteenths of an inch long. Most of them are brownish to grayish yellow and flat, as though compressed from above.

Lousiness can be detected by parting the feathers and looking for the insects on various parts of the body. They may be found on the skin, the shafts of the feathers, or the fluff of the feathers. All but a few species can dart among the feathers so quickly that some experience may be necessary to find them unless great numbers are present. Their eggs sometimes may be seen in large masses at the base of the feathers. Some species lay their eggs singly on the feathers, and then the eggs may escape detection. All bird lice have biting or chewing mouth parts and ordinarily eat castoff bits of skin and feathers.

All have similar life histories. They are permanent parasites, spending their entire lives on the birds. They die in about 5 or 6 days if they are removed from the living fowl. Louse eggs require a week or less to hatch. The adult stage is reached in 3 weeks or less. The young lice molt two or three times in that time.

Mating takes place on the birds.

Egg laying may begin 2 or 3 days later. Each female may lay as many as 300 eggs. Because one pair of lice may produce 120,000 descendants in a few months, infestations can increase fast. In cold weather, when the heaviest infestations occur, 6 thousand to 7 thousand lice may be present on a single chicken. Infestations are acquired through contact; the lice crawl from one bird to another.

Chicken lice are identified commonly by their usual location on the body. We therefore call them head lice, wing lice, body lice (or vent lice), and shaft lice. Such distinctions are not always satisfactory, for in heavy infestations the vent louse can be found anywhere on the skin, the head louse on the neck and sometimes over the body, and the wing louse on the tail and back feathers. Three or more species may be on a bird at one time.

The body, or vent, louse (Menacanthus stramineus) is one of the commonest parasites of poultry everywhere in the United States. It is large, vigorous, and active. It is the most destructive species found on adult birds, where it congregates on the skin just below the vent. Extremely heavy infestations may be on the back, under the wings, and, in fact, from head to the thighs. In young chickens it is found commonly on the back. Its eggs often are in large clusters at the base of the feathers around the vent.

The chicken head louse (Cuclotogaster heterographus) also is of primary importance. A grayish louse, it is found on the head and neck. It may cause considerable injury to young chicks. Its eggs, laid singly, are attached to the down or fine feathers of the head.

The shaft louse (Menopon gallinae) is widespread. It is a parasite of adult birds. It is pale yellow. You can usually see it when parting the feathers of the thighs and breast; then, in heavily infested fowl, you can see a row of the lice running quickly down the shafts and dispersing when they reach the skin. The eggs are deposited singly at the base of the shaft.

The wing louse (Lipeuris caponis) is grayish. It infests the underside of the primary wing feathers or in heavy infestations, the tail and back feathers. It does not move about a great deal. It is easily detected, especially on white birds. Its eggs are laid on the large wing feathers and are not readily seen.

Two other species likely to be found on chickens throughout the United States are of minor importance. The fluff louse (Goniocotes gallinae) is pale yellow and so broad that it appears almost circular. Small numbers of this little louse may be found on the fluffy feathers anywhere on the body. Like the wing louse, it is rather sluggish.

The large chicken louse (Goniodes gigas) is widely distributed geographically, but only a few are apt to be on a bird at one time. It is the largest, darkest, and most formidable looking of the lice on chickens, and can be seen anywhere on the body as it darts among the feathers.

TURKEYS MAY BE INFESTED with five species of lice. Three of these the vent louse, the shaft louse, and the head louse of chickens may be abundant.

Two others, the large turkey louse (Chelopistes meleagridis) and the slender turkey louse (Oxylipeurus polytrapezius), appear to be restricted to turkeys.

Lice do not appear to be abundant on ducks and geese or to cause appreciable injury.

Several species attack pigeons. The large pigeon louse, the small pigeon louse, and the slender pigeon louse are most important. All three species may attain large enough numbers to cause injury.