GALLS CAUSED BY BEETLES 47 



The duration of the pupal state is short, usually varying 

 from one to three weeks. Beetles chiefly pupate in the 

 earth or near the feeding-place; many species make a 

 cocoon of bits of earth or wood. The pupa is usually soft. 

 The imago is soft and almost colourless upon emergence, 

 and sometimes takes several days to attain normal colora- 

 tion and hardness. The use of the beautiful sculpturing so 

 frequently seen on the elytra is quite unknown. Beetles 

 are difficult to rear, and, considered collectively, very little 

 is known about their life-histories. Dr. Sharp observes 

 that " they exhibit, however, extreme diversity correlative 

 with the great specialization of so many beetles to particular 

 kinds of life. Most beetles must have exactly the right 

 conditions to live in." Thus, many families of plants are 

 free from coleopterous parasites, whilst others are infested 

 with many, and the gall-causers in a particular family are 

 generally members of a single genus. 



Amongst the Leguminosae we find numerous galls caused 

 by species of the genus Apion. As a rule, the flowers and 

 stems are attacked. The beetles of this genus are popularly 

 known as " pear-shaped weevils," the long and arched pro- 

 boscis and globose body causing a resemblance to a long- 

 stalked pear. 



The larvae of Apion scutellaye cause ovoid or rounded 

 swellings about the size of a large pea on young stems of 

 the Common and Lesser Gorse, and those of A. immune 

 give rise to similar deformities on the Broom. Clovers 

 frequently sufifer from the attacks of various species — e.g., 

 the Purple Clover is infested by A. assimile, A. varipes, 

 and A . apricans. A , varipes causes excrescences to arise on 

 the roots ; the others attack the flowers, and the floral axis 

 becomes hypertrophied, 



Apion Gyllenhali attacks the stems and petioles of Vetches. 

 Amongst the Labiatae we also find Apion vicinium infesting 

 the Catmint and other species, the larvae living in a multi- 

 locular swelling on the stem. 



In the Compositae Apion sorbi attacks Chamomiles (An- 



