FEATHER LICE I I9 



parasitic on birds and later spread to mammals, but here we are con- 

 cerned only with the species living on birds. 



Habits And Structure 



To the naked eye the Mallophaga are not unlike small free-living 

 insects. Actually, however, considerable structural modifications have 

 taken place : chief amongst these is the general flattening of the body 

 (dorso-ventrally, not from side to side as in the flea), which enables the 

 insect to sHp between the feathers and to apply itself to their flattened 

 surfaces for the purposes of feeding and attachment. The head, 

 especially, has become modified. In a free-living insect, such as the 

 cockroach, or in an animal Hke a horse, the longer axis of the head hes 

 at right-angles to the rest of the body. In the Mallophaga the head has 

 become flattened from top to bottom so that the longer axis Hes in the 

 same plane as that of the body. The head is a hollow box-like structure 

 with thickened walls; these have thinner areas (or sutures, Plate XXI) 

 allowing a Hmited mobihty of the parts of the head for feeding. On the 

 inner surface of the walls are various thickened ridges (Plate XXI) 

 which give strength to the head and form a supporting framework for 

 the mouth-parts. These sutures and ridges are useful characters in 

 classifying the genera of the Mallophaga. 



The feather hce, unhke the fleas, show considerable diversity in size 

 and general body form (Plates XXII-XXIII) . This diversity has been 

 brought about by the Mallophaga occupying the different types of 

 habitat, such as the head and the wings, found on the body of the bird 

 and becoming speciahsed and adapted for life in these locations. 



In size feather Hce range from the minute game-bird-infesting 

 Goniocotes, in which the males are just under a millimetre in length — 

 a Htde less than the proverbial pin's head— to the large hawk-infesting 

 Laemobothrion which may be up to ten millimetres (about one-third of 

 an inch) in length. 



Feeding, The Mallophaga, originally feeders on various kinds of 

 organic debris, took to eating feathers when they became parasitic on 

 birds. This change of diet did not necessitate any fundamental modi- 

 fications in the original chewing mouth-parts, which were probably 

 similar to those found in an unspecialised insect Uke the cockroach. 



