PSE UDONE UROP TERA . 8 3 



C. pulsatoria is a little more than i mm. in length. It is of a pale 

 yellowish white, and is found in similar situations as the book-louse. 



PSOCIN^E. Here we find four well-developed wings. Usually 

 these extend much beyond the end of the abdomen. But short- 

 winged forms occur in species which ordinarily are long-winged. Of 

 course the young of all are wingless, and there is a gradual develop- 

 ment of the wings as the insect matures. The antennae consist of 

 only thirteen segments ; this will enable one to separate the imma- 

 ture forms from the Atropinae. 



The Psocinse occur upon the trunks and leaves of trees, on stones, 

 walls, and palings. They feed upon lichens, and probably other dry 

 vegetable matter. They are sometimes gregarious. I have often 

 observed communities of a hundred or more closely huddled together 

 on the trunks of orange-trees in Florida, feeding upon lichens. 



The eggs are laid in heaps on leaves, branches, and bark ; the 

 female covers them with a tissue of threads. It is believed that 

 both sexes have the power of spinning threads similar to those spun 

 by spiders. 



Several genera of Psocinae occur in the United States ; but the 

 greater number of our species belong to the genus Psocus. 



Family VI. MALLOPHAGID^* 



Order MALLOPHAGA of some authors. 



(Bird-lice.) 



The Mallophdgidce are parasites which live on warm-blooded ani- 

 mals. They infest chiefly birds, and on this account the term Bird- 

 lice is applied to the entire group. A few genera, however, are 

 parasitic upon mammals. It is an interesting fact 

 that in the case of the genera that infest mammals 

 none of the species are found on birds ; and of 

 those that live on birds none infest mammals. 



The bird-lice resemble the true lice in form, 

 being wingless, and with the body more or less flat- 

 tened. Certain species which infest domestic fowls 

 are well-known examples. These insects differ from 

 the true lice in having biting mouth-parts. They 

 feed upon feathers, hair, and dermal scales, while the ul (From Law.' 

 true lice (Family Pediculidae, Order Hemiptera) have 

 sucking mouth-parts, feed upon blood, and infest only mammals. 



* MallSphaga: mallos (//aAAdc), wool; phagein (<t>ayeir), to eat. 



