ARTHROPODA 



contain Chalcis larvae which have devoured the gallfly 

 larva. Some chalcids lay their eggs on the skin of the 

 host as in the case of Euplec- 

 trus (Fig. 58), while others 

 insert the eggs within the tis- 

 k sues and the larva? do not 



Jfc AK appear on the surface until 



^11 they are ready to spin their 



cocoons. 

 That the chalcids are most 



FlG. 59. Chalcids transformed 

 from the larvae shown in Fig. 58. 

 Photographed nine days after Fig. 

 58. Enlarged eight times. 



effective helps to man may be 

 seen from the fact that in one 

 year in the cotton fields of 

 Florida ninety-five per cent of 



the eggs from which would have hatched the destructive 

 cotton caterpillar were killed by a species of Chalcis. 



4. LEPIDOPTERA 



This order includes the butterflies and moths, which are 

 readily distinguished from other insects by the presence 

 of two pairs of wings covered with scales. In a few species 

 the female has no wings. Butterflies usually fly by day 

 and moths by night. When resting the wings of a butter- 

 fly are held vertical over its back, but a moth at rest 

 holds its wings expanded or lying flat on its back. The 

 antennae of a butterfly are clubbed or enlarged at the 

 end, while those of a moth taper and are often feathered 

 throughout. The larvae of butterflies never construct co- 

 coons, while those of most moths spin or weave cocoons 

 for the pupal stage. 



