1924 ENTOMOLOGICAL SOCIETY 69 



Bird lice are all included under the order Mallophaga, and live by feeding on 

 the epidermal products such as feathers, scales, etc. Blood dried on the skin 

 may be eaten, but bird lice are not bloodsuckers. 



Since they do not pierce the skin their depredations may be less inimical 

 to the welfare of the host than the activities of the suctorial variety. 



While these prefatory remarks may seem rather foreign to the subject in 

 hand, they appear relevant in view of the fact that a traditional belief exists 

 amongst poultrymen that the head louse, Lipeurus heterographns, is responsible 

 for a heavy mortality amongst young chicks. 



This parasite is well called the head louse, because of its predilection for 

 this portion of the body. Infestation is most prominent on the feathers of the 

 head and neck, although a few lice are occasionally found on the feathers of the 

 wings. It has often been stated that lice dig into the flesh and even eat the 

 brains of chickens. Undoubtedly this is the species that has caused this mis- 

 conception. Often it is found on a feather with its head close to the body of the 

 chicken but apparently never imbedded in the skin. 



The head louse is much darker in colour than the ordinary body lice of 

 poultry, Menopon pallidum and Menopon biseriatum, and is quite easily seen 

 when the feathers, especially if white, are separated. The body is edged with 

 dark bands and there are markings of the same shade across the abdomen. The 

 first segments of the antennae of the male are very large and the third segments 

 are branched, while the antennae of the female are more slender. This louse 

 averages slightly less than one-tenth of an inch in length. 



It is much less active than the body lice, but can easily slip between the 

 barbs of the feathers and disappear from sight. It can live away from the fowl 

 at normal temperatures for a longer period than the body lice, probably because 

 it is accustomed to the cooler region of the feathers. 



The eggs are glued to the feathers of the head and neck, being attached to 

 the barbs often between the shaft and aftershaft. Observation has shown, that 

 the eggs hatch in from four to five days during warm weather, but the period 

 may be extended during the cold months of the year. Our own experience 

 shows that the time necessary to complete the life cycle from egg to adult during 

 moderately warm weather is about twelve days but this is undoubtedly subject 

 to seasonable variation. 



To determine whether or not the head louse was capable of causing a heavy 

 mortality amongst young chicks, experiments were undertaken during the 

 summer of 1922. 



On June 17th, two chicks sent in for autopsy were found to be infested with 

 head lice, and on the following day three chicks about one month of age were 

 infected to propagate a sufficient number for experimental work, an average of 

 six to eight mature lice being placed upon each bird. 



On July 7th, these three chicks were found to be heavily infested, making 

 the further carrying on of experimental work possible. 



On August 12th, thirty chicks were selected from a newly-hatched bunch 

 of incubator birds and were divided into two pens of fifteen birds each. 



These chicks were fourteen days of age and had been carried through to 

 this period to eliminate weaklings. 



On August 12th, one pen comprising fifteen chicks were infected with head 

 lice from the older birds, from six to ten adult lice, males and females, being 

 placed upon each chick, by pulling the feathers with adhering lice from the older 



