228 



AN INTRODUCTION TO ENTOMOLOGY. 



fully grown this larva measures from 7 to 10 mm. (0.3 to 0.4 in.) in 

 length. It then spins a cocoon, and changes to a pupa within the 

 skin of the larva. Later the larval skin is cast ; and, finally, after 

 being in the cocoon about a month, the pupa becomes active, pierces 

 the cocoon and the egg-sac, crawls about for a time, and then 

 changes to the adult state. 



Family III. — PANORPIDiE.* 

 Order MECOPTERAf of some authors. 

 {Borcus, Scorpion-flics, ct al.) 

 is a small family ; but it is composed of very remarkable 

 insects. The most striking character common to all 

 is presented by the mouth. This is prolonged into 

 a rostrum, as shown in the figure. The body is 

 cylindrical or conical ; the head is exserted ; the 

 prothorax is small ; and the tarsi are five-jointed. 

 So far as is known the members of this family 

 are carnivorous. There are only four described 

 genera. These can be separated by the following 

 table : 



This 



Fig. 194. — Head 

 and tail of Pa- 

 norpa. 



BOREUS. 



Panorpa. 



BlTTACUS. 



Merope. 



A. Wingless or with rudimentary wings. 

 AA. With well-developed wings. 

 B. Wings narrow ; antennae setaceous. 

 C. Tarsi with two serrated claws. 

 CC. Tarsi with a single simple claw. 

 BB. Wings broad ; antennae short, thick, the apex narrowed. 



Borcus. — Among the few insects that occur on the snow, in the 

 winter, in our Northern States, are two species of the genus Boreas. 

 In this genus the wings of the female are very rudimentary; those 

 of the males are about half as long as the abdomen, narrow, stiff, 

 and entirely useless for flight. Borcus nivoriiindus, the Snow-born 

 Boreus, is shining black or brownish black, with the rudimentary 

 wings, thorax above, and the rostrum and ovipositor excepting their 

 tips, tawny. The male measures 3 mm. (0.12 in.) in length; the fe- 

 male, including the ovipositor, 4^ mm. (0.16 in.). The Midwinter 

 Boreus, B. brumalis, is smaller; the male measuring 2^ mm. (o. 1 in.), 

 and the female 3 mm. (0.12 in.), in length. This species is deep black- 



* Panorpidse, Panorpa: pan (tzocv). all; horpe = harpe (apmf), a sickle, 

 f Mecoptera, incorrectly written Mecaptera: mecos (juf/KoS), length ; pteron {nrepov), 

 wing. 



