92 THE GROUP OF PAMPHTLIUS ERYTHROCEPHALUS. 



species ; it is common in North America, two species 

 are known from Mexico, but none south of that ; a few 

 species are found in China and Japan. 



It can be arranged into several well-marked groups 

 (sub-genera) by the differences in the form of the head, 

 the structure of the antennae, and arrangement of 

 spines on the tibiaB, and by the neuration. 



SECTION 1. Anterior tibiae with a spine ; calcaria bifid, 

 with a small tooth beloiv the apical one ; vertex with- 

 out sutures, or with them very thin ; the central 

 region not separated from the sides, but continuous 

 with them. Subcostal nervure furcate beyond the 

 middle, transverse brachial nervure obsolete. 



The first two groups are clearly separated from the 

 rest of the genus by the spines on the front tibiae, by 

 the obsolete transverse brachial nervure, and by the 

 head wanting sutures on the vertex. Their antennae, 

 too, are longer, and have more joints (twenty-five to 

 thirty-five) than usual. Although the larvae struc- 

 turally do not differ from those of the other species, 

 yet they agree in habits, and especially in being attached 

 exclusively to pines. 



In Britain neither group is well represented. On the 

 Continent there are three species of Group I and five 

 of Group II. 



I. THE GROUP or PAMPHILIUS ERYTHROCEPHALUS. 



Body blue or violaceous, with the head in ? red, wholly or in part. 

 Wings violaceous. Antennae long, the third joint as long 

 as the following three; 25 32-jointed. 



