CHAPTER XXII 



THE LARGE CABBAGE WHITE BUTTERFLY 



THE large cabbage white is one of the most common of our 

 English butterflies, so much so that at times its larvae do serious 

 injury to crops of cabbages and other garden plants on which they 

 feed. There are two broods and sometimes three in the course 

 of the year, the perfect insect appearing first in May and June, 

 and again in July, August, and, if the season be a late one, Sep- 

 tember ; or the third brood may appear in September if the im- 

 mediately preceding conditions have been unusually favourable. 

 There is therefore but little difficulty in procuring specimens at 

 any time during the summer months. 



Head. The head of the butterfly is rounded ; at its sides 

 it carries a pair of large black compound eyes, and between these 

 on the dorsal surface three simple eyes the ocelli. These last 

 are not easy to make out, because they are concealed among 

 the hairs that clothe the head. From the front of the head above 

 the eye there stand out a pair of antennae, whose distal joints 

 are rather abruptly different in shape from their predecessors, 

 being shorter and stouter, so that the whole antenna is club 

 shaped. This shape is a feature by which butterflies may easily 

 be distinguished from moths ; but the exact form of the " club " 

 differs in different butterflies, e.g. in the now scarce Black-veined 

 White the passage from long and narrow to short and stout joints 

 is bridged by intermediate joints, so that the transition is gradual. 

 All the uses of the antennae are not fully understood, but there is 

 little doubt that they contain sense organs which correspond 

 with those of smell in ourselves, and in this manner they enable 

 the opposite sexes to find one another. Projecting between the 

 antennae from the under side of the head is a pair of short, pointed, 

 scale-clad palps the labial palps ; these consist of three joints, 

 but are so densely covered with hairy scales that the fact may 



181 



