126 AN INTRODUCTION TO ENTOMOLOGY. 



Sub-Order II.— TEREBRANTIA.* 



This sub-order is characterized by the presence in the female of 

 a four-valved borer. The maxillary palpi are three-jointed; the two 

 pairs of wings differ somewhat in structure ; the first pair is some- 

 what longer, and wider, and usually also thicker ; sometimes they 

 are almost horny ; both pairs are clothed with numerous very fine 

 hairs ; the front wings have two parallel veins, the hind wings a 

 single vein or none ; the veins of the wings usually bear conspicu- 

 ous spines ; the wings, when not in use, are folded parallel to each 

 other on the abdomen. 



The members of this sub-order are much more agile than those 

 of the preceding. They run rapidly, and spring, by bending under 

 the tip of the abdomen and suddenly straightening it out. 



The Terebrantia includes two families ; these can be separated 

 as follows : 



A. Females with borer curved downwards. Fam. II. — Stenopterid^e. 



AA. Females with borer curved upwards. Fam. III. — Coleoptratid/e. 



Family II. — STENOPTERiD.E.f 



In the Stenopteridae the wings are narrow and are furnished 

 with one or two longitudinal veins ; but there are no cross-veins. 

 The longitudinal veins are usually fringed with spines. There are 

 two or three small indistinct segments at the end of the antennae. 

 And, as stated above, the ovipositor of the female is curved down- 

 wards. This family includes the greater number of the members of 

 the order. The following table will aid in determining the genera: 



A. Body above netted with elevated lines. i. Heliothrips. 

 AA. Body smooth. 



B. Abdomen clothed with silky hairs. 2. Sericothrips. 

 BB. Body glabrous. 



C. Prothorax produced in front and narrowed. 3. Chirothrips. 

 CC. Prothorax not narrowed. 



D. Last segment of abdomen armed with paired spines in the female ; 



male wingless. 4. Limothrips. 

 DD. Last segment unarmed. 



E. The last two segments of the antennae shorter than the sixth 



segment. 5. Thrips. 



EE. The last two segments of the antennae longer than the sixth 



segment. 6. Belothrips. 



* Terebrantia: terebro, to bore through. 



f StenoptSridae: stenos (arevoS), narrow; pteron {nrepuv), a wing. 



