MOTHS OF THE LIMBERLOST 



The thorax bears four wings, and six legs, each having 

 five joints and ending in tiny claws. The wings are 

 many-veined membranous sacs, covered with scales that 

 are coloured according to species and arranged to form 

 characteristic family markings. They are a framework 

 usually of twelve hollow tubes or veins that are so con- 

 nected with the respiratory organs as to be pneumatic. 

 These tubes support double membranes covered above 

 and below with down. At the bases of the wings lie 

 their nerves. The fore-wings each have a heavy rib 

 running from the base and gradually decreasing to the 

 tip. This is called the costa. Its purpose is to bear the 

 brunt of air-pressure in flight. On account of being 

 compelled to fly so much more than the females, the back 

 wings of the males of many species have developed a 

 secondary rib that flts under and supports the front, also 

 causing both to work together with the same impulse to 

 flight. A stiff bunch of bristles serves the same purpose 

 in most females, while some have a lobe extending from 

 the fore-wing. As long as the costa remains unbroken 

 to preserve balance, a moth that has become entangled 

 in bushes or suffered rough treatment from birds can fly 

 with badly damaged wing surfaces. 



In some species, notably the Attacine group and all 

 non-feeding, night-flying moths, the legs are short, 

 closely covered with long down of the most dehcate 

 colours of the moth, and sometimes decorated with dif- 



43 



