82 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



variation, etc., arise out of a consideration of the geographical and host 

 distribution of these parasites. They are wingless insects of world- 

 wide distribution existing wherever members of the bird tribe are 

 found. They are parasites that live for their whole life on the body 

 of their host. They, of course, migrate from one host to aAother when 

 the hosts are in actual contact, when in copulation; when brooding 

 over the offspring; or when huddling together on perches. More- 

 over there is occasionally an opportunity for the parasites of a host to 

 actually migrate to a host of another species. For example, we find 

 a certain species of hen louse on the turkey, especially when the two 

 species of domestic fowls are in the same yard. We have also found 

 two species of hen lice on guinea hens where the latter were allowed to 

 frequent the perches and houses of the hens. Kellogg has found the 

 same species of louse on both a cormorant and a pelican shot on the 

 rocky shores of the Pacific Coast where these two species of birds con- 

 gregated and evidently came in actual contact. But as Kellogg further 

 points out another explanation must be given for the distribution of 

 those species of Mallophaga that are found on birds of the Old World 

 and on closely related birds of the New World. There are many in- 

 stances of this kind, yet these birds do not come in contact, nor within 

 thousands of miles of each other. Kellogg offers an exceedingly inter- 

 esting explanation of this phenomenon in distribution. He says, 

 "that the parasitic species has persisted unchanged from the common 

 ancestor of the two or more now distinct but closely allied bird-species." 

 That is to say, these species of Mallophaga existed on the ancestors of 

 the host birds and have persisted ever since without change although 

 their hosts have become modified into different species. This may be 

 explained by the fact that the Mallophaga are surrounded by an en- 

 vironment, namely, the feathers, skin, and temperature of the host, 

 that do not change although the host itself may change. These are 

 not economic questions perhaps but they are intensely interesting 

 ones. 



The more important question from an economic point of view is 

 how these parasites injure poultry. The Mallophaga have biting 

 mouth parts and do not suck the blood of their host. In fact, it is 

 doubtful if any of the Mallophaga parasitic on domestic fowls ever 

 get any blood except in case of a wound or bruise on the host from 

 which the blood may issue. In such instances the parasites may eat 

 the dried scales of blood. Blood has been found in some instances in 

 the stomachs of bird lice, probably obtained in the manner just de- 

 scribed. Kellogg notes a species of Mallophaga that lives inside of 

 the pouch of the California Brown pelican and clings to the wall of 

 the pouch by its mandibles. Moreover, he has found a small area 



