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 scuiellare 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 suffer from the attacks of various species— e.g., 
the Purple Clover is infested by A. assimiie , 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 GyllenhaU attacks the stems and petioles of Vetches. 
Amongst the Labiatae we also find Apion vicimum 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- 
