IV. INSECTA: HEXAPODA, HYMENOPTERA. 485 



penult joint rudimentary, giving the impression of four joints. The 

 families included here*- very numerous in species, are injurious to vegeta- 

 tion. The larvae of the long-horned CERAMBYCID.E bore in wood. The 

 CHRYSOMELID^E, of which the Colorado potato beetle (Dory- 

 phora decemlineata) is the most notorious, feed on 

 leaves. 



Sub Order IV. TRIMERA ; tarsi with penult and anti- 

 penult joints rudimentary, so that they appear three- 

 jointed. Best known are the COCCINELLID^E, or lady birds, 

 whose larvae, because of their destruction of plant lice, 

 etc., are of value to man. 



Sub Order V. RHYNCHOPHORA, snout beetles ; head 

 produced into a long snout, at the apex of which are the 

 mouth parts. Here belong several families of weevils, FIG 517. 

 some of which do damage to grain, nuts, timber, etc. U2Jel-nut**wee! 

 Curculio* Conotrachelus * Calandra* Hylesinus* Bala- vil. 

 ninus* (fig. 517). 



Order VII. Hymenoptera. 



The Hymenoptera, of which bees, wasps, and ants are well- 

 known representatives, have biting jaws, while the other mouth 

 parts are elongate and in a minority of the group converted into a 

 sucking organ. In the bees (fig. 48?) the glossa unite, producing 

 a nearly closed tube, which lies in a sheath formed by the other 

 mouth parts, the mandibles alone retaining the primitive form. 

 Since mouth parts vary, the structure of the wings and body seg- 

 mentation have great value in defin- 

 ing the order. The wings are mem- 

 branous and are supported by few 

 nervures (fig. 518), and in flight they 

 act as one pair, since the two are 

 usually connected by hooked bristles 

 on the hind wing, which engage in 

 a groove on the hinder margin of 

 the front wing. The fore wings are 

 the larger and, correspondingly, the 

 mesothorax exceeds the other tho- 

 racic somites, so that these, especially 

 FiG.5i8.-sir*r0/0a,sawfiy. (After the prothorax, seem but parts of the 



strong mesothorax. Besides, the first 



abdominal ring unites to the thorax so intimately in the En- 

 tophaga and Aculeata as to seem part of it. The constriction 

 which then separates thorax and abdomen comes between the first 

 and second abdominal somites, and when the second (petiole) is 

 elongate the stalked abdomen, familiar in the wasps, results. 



