100 ELEMENTARY LESSONS ON INSECTS 



5. The "fireflies": These are not flies at all, but true 

 beetles, rather soft-bodied, with loose-fitting wing covers. 

 They are obscure beetles that would hardly be noticed but 

 for their remarkable powers of illuminating the black sum- 

 mer night with little flashes of light. 



Note: 



(a) The stout antennae, toothed on one edge like a saw. 



(b) The wide prothorax, with margins flaring at the sides 

 and also in front where it more or less completely 

 covers the head. 



(c) The yellowish spots underneath one or more of the 

 abdominal segments where the light organs are sit- 

 uated. 



6. The blister beetles (Fig. 37): Long-legged, nearly cylin- 

 dric in form, diurnal in habits, commonly found in autumn 

 feeding on the leaves of potatoes and other plants and on 

 the pollen of goldenrods. The defensive secretion that is 

 produced by the living insects has the property of blister- 

 ing the human skin ; and in former times an old world species, 

 known as the "Spanish fly," was dried and powdered to 

 make blister plasters. 



Note especially: 



(a) The long antennae. 



(b) The slender form. 



(c) The four-jointed hind tarsi. 



7. The click beetles: Smoothly contoured, elongate-oval, 

 often very handsome beetles, having a shield-shaped pro- 

 thorax with projecting hind angles and a remarkable joint 



