COLEOPTERA 213 



live on or in their food, are footless grubs. The pupa is 

 generally soft and pale, enclosed in a cocoon, and concealed 

 in earth or wood. A thin and transparent pupa-skin covers 

 the body, which is practically the body of the future beetle ; the 

 appendages of concealed pupseare often nearly or altogether 

 free. Exposed pupae may resemble Lepidopterous pupae in 

 being covered with a protective varnish, which glues the 

 limbs to the body. The duration of the preliminary stages 

 varies greatly according to the food, as is the case with other 

 orders of insects also. Larvae which burrow in _ the ground 

 or in the trunks of trees are of slow growth, and may feed 

 for two or three years, usually resting in the winter. On 

 the other hand, some leaf-eating beetles condense the 

 whole life-history into a few summer weeks. 



Mode of life, etc. — Beetles often pass their whole life 

 underground or in concealment, and are then usually dark- 

 coloured. Many that appear on the bark of trees are brown, 

 and leaf-eating species are often green. The coloration is 

 not, however, always directly protective. Some beetles which 

 are conspicuously coloured are either acrid or particularly 

 hard-shelled, so that they are distasteful to birds. In very 

 many cases the advantage of the peculiar coloration has not 

 been discovered. 



Beetles are eminently a dominant order of insects, abound- 

 ing both in species and in individuals ; the species are often 

 very hard to distinguish. It seems to be a general mark 

 of dominant groups that in them species which differ very 

 slightly can maintain themselves side by side. 



The Families of Ooleoptera 



None of the many attempts to arrange the Coleoptera in 

 a few large groups can be considered altogether successful. 

 The number of the joints in the tarsus and the form of 

 the antennae yield useful characters, but if they are employed 

 too rigidly, natural groups are broken up. The primary 

 groups of beetles, as defined by recent students, and the 

 chief families found in the British Isles, are characterised in 

 the following table, where short notices will be found of 

 interesting beetles which we have not space to describe at 

 length. 



