352 TEXf-BOOK OF ZOOLOGY 



process is somewhat like " snapping one's fingers," in which act we press 

 the middle finger firmly against the thumb (abutment) and allow it 

 to glide off suddenly; in this way much force is exerted, and, as is 

 well known, a slight explosive sound produced. With this peculiar 

 faculty of motion of the Elateridse, the great mobility of the .first thoracic 



An Elater (Skipjack). 



At 1, lying on its back ; at 2 and 3, in the act of skipping, and thereby, as shown in 4, 

 landing upon its legs. D., Spine of the first thoracic segment (prothorax). 



segment (prothorax) and the elongated shape of these insects are closely 

 correlated. 



The " wire-shaped " larvae of several of the Elateridse, bearing a strong 

 resemblance to the well-known meal-worm, are known as "wire-worms," 

 and often do considerable damage by destroying the underground portions 

 of the stems of root, grain, and fodder crops. One of the most destructive 

 is the Striped Click Beetle (Agriotes lineatus). It measures about \ inch 

 in length, and is dark gray with yellowish striped wing-covers. 



Family 6 : Malacodermata. 



The Glow-worm (Lampyris splendidula). 



(Length about £ inch.) 



On warm summer nights — about St. John's or Midsummer Day — 

 meadows and bushes are frequently illumined by numerous radiant little 

 lights. They are the lamps lit by the glow-worm, or St. John's worm, 

 as it is called in Germany, from the time of its appearance. If one of 

 these fiery sparks is caught in its flight through the air, it will turn out 

 to be the male of this beetle, which is of a grayish-brown colour, with 

 two colourless transparent spots on the prothorax, and with leathery, 

 soft wing-covers. If, on the other hand, one of the small lights is taken 



