408 



Biology in America 



tim, the fertilized female drops to the ground, and deposits 

 on the avoi-age about 2,000 sliiny brown eggs about 1/50 

 inch in diameter. These hatcli in about three weeks in 

 summer, while in winter incubation may require nearly six 

 months. After hatching the young tick becomes ambitious, 

 crawling up blades of grass, stems, or posts and there waiting 

 like Mr. Micawber "for something to turn up." Meantime 

 it keeps its forelegs waving to and fro ready to grasp the 



"Screw Worm" and Cattle Tick 

 A — A "screw worm," the larva of a fly, so-called from the rings of 

 spines about tlie body. 



C and B — Cattle ticks before and after feeding. 



donrtiKji itj the V. S. liiiniiK of Kiitomolog}/. 



hair of the first animal which comes its way. It may thus 

 patiently await its victim for more than five months, under 

 favorable conditions, but the victim failing to arrive it finally 

 dies. If an unlucky steer comes its way it grasps its hair 

 and crawling up attaches itself to the skin. Here it molts 

 twice, is fertilized, gorged with blood, and drops to the ground 

 to repeat the vicious cycle. 



