COCOON, PUPA, AND MOTH 27 



nous tube called the costa^ the strongest part of the 

 wing, as it has to meet the greatest pressure of the air. 



If the two wings on the same side were not held 

 together they would move sejDarately and not serve 

 their purpose as well. On the hind wing of most 

 males there is a stiff spine which extends under the 

 fore wing, preventing it from slipping by the hind 

 wing. The females have a bunch of stiff bristles 

 which serve the same purpose. This is called the 

 fren'ulum. A few moths have no frenulum, but have 

 instead a lobe extending backward from the hinder 

 edge of the fore wing, and answering the same pur- 

 pose. This iobe is called a ju'giim. A few have 

 neither. A hand-lens magnifying fifteen or twenty 

 diameters will show the scales fairly well. The wings 

 are brittle and easily broken, but it requires much 

 destruction of wing surface to disable the moth so 

 that it cannot fly. The wing muscles are very strong, 

 as may be proved by holding a sphinx moth by the 

 fore wings and feeling the force of its struggle to free 

 itself. 



The females of some moths have the wings hardly 

 developed enough to show, and never fly, but stay near 

 the spot where they emerge, often laying their eggs 

 on the cocoons from which they came. 



On top of the thorax, near the head, are two small 

 flaps, usually densely covered with scales, called the 

 pata'gia. They seem to have no use now, but are often 

 very ornamental. They are movable and may be 

 erected. 



The very soft abdomen is plainly divided into seg- 

 ments, while the divisions of the thorax are not seen 



