INSECTS IN RELATION TO BIRDS. 555 



The relation between insects and birds is somewhat different. This 

 class, which we have found analogous to insects in their type of organ- 

 isation, overlooking their internal skeleton, stand in the closest relation 

 to insects. This relation is double, as we find insects deriving their 

 food from birds, and birds again feeding upon insects. With respect 

 to the first, there is probably not a single bird which is not inhabited 

 by one or even several clearly distinct species of parasitic insects, and 

 which even sometimes belong to distinct genera. All these insects 

 form a peculiar large group among the parasites, which Linnaeus classed 

 with the lice, but which De Geer, from their mandibulate oral organs, 

 separated by the name of Ricinus, from the lice (Pedicuhts) , and 

 Nitzsch, lastly, collected together in a separate family which he called 

 Mallophaga (fur destroyers), and classed with the Orthoptera. Their 

 most correct situation is perhaps amongst the Diciyotoptera, with 

 Avhich we formerly placed them. This group falls into four very 

 natural genera, of which Philopterus and Liotheum are the most 

 numerous, and are distributed among all species of birds; Trichodectes 

 and Gyropus are the smallest in number, and are found only upon the 

 mammalia, namely, upon beasts of prey, the Glires and the Rumi- 

 nantia, they dwell between the softer down or woolly hairs, and feed 

 upon that and not upon the blood of the animal, at least Nitzsch found 

 in all those which he anatomically investigated portions of down in 

 their stomach *. Besides this large group there are smaller genera and 

 species, which likewise live as parasites upon birds, especially upon 

 young nestlings, particularly the genus Carnus, discovered by Nitzsch, 

 upon young starlings, a form allied to the Conopica, as well as the 

 genera Ornithomya, Lat., and Strebla, Wied, both of which belong to 

 the pupiparous family of the Diptera, which are found upon other 

 young birds, especially swallows. 



Insectivorous birds are those chiefly which belong to the Passerines 

 and the Cuculines. The Laniadce feed almost exclusively upon insects, 

 but some are said also to prey upon small warm-blooded vertebrata. 

 The Coraces, or crows, devour chiefly carrion, but also very many feed 

 upon insects, namely, the jays and blackbirds ; some also eat fruits, which 

 we find likewise in the true singing birds. The genera Fringilla, Em- 

 beriza, Tanagra, and Euphone eat fruits and seeds ; Sylvia, on the 



* See Nitzscli iiber die lAimilicii und Gattungcn der Thierinsekten, In Gcrmar's 

 Magazine, vol. iii. p. 261. 



