Fig. 30 

 Turnip-flea. 



been 



40 INJURIOUS AND USEFUL INSECTS 



The four joints of the tarsus indicate a section of Coleoptera 

 known as Tetramera, which are also called Phytophaga, from 

 their taste for vegetable food. Close examina- - 

 tion shows that there are really five joints in 

 the tarsus, but that the fourth is reduced to 

 a vestige of no practical use. 



The phytophagous beetles are divisible into 

 three famihes : — (i) Seed-eaters (Bruchidse), 

 often confused with weevils; the so-called 

 pea-weevil is an example ; (2) the Leaf-eaters 

 (Chrysomelidae), to which the flea-beetle be- 

 longs ; and (3) the Longicorns or wood-eaters 

 (Cerambycidae), named Longicorns from their 

 long feelers, which often exceed the body in 

 length. 



The flea-beetle feeds on all Cruciferous 

 1. plants, whether wild or cultivated, and is 

 often found in places where turnips have 

 grown. Large crops of turnips give it, of 

 course, facilities for food and increase, which do not exist 

 elsewhere. This beetle is active throughout the warm season, 

 and produces several broods in close succession ; in winter 

 it seeks shelter, and is rarely seen. 



The eggs are laid singly on the under side of leaves. The 

 larva which issues from the egg is small and of pale yellow 

 colour. It has 

 a dark-coloured 

 head, and three 

 pairs of rather 

 stumpy legs ; the 

 end of the abdo- 

 men bends down 

 and forms a sup- 

 port. It is a leaf- 

 miner, burrowing 

 in the thickness 

 of the leaf, eating 

 up the green sub- 

 stance, and leaving a sinuous discoloured track or burrow, 

 where only the dead cuticle is to be found. The habit of 

 leaf-mining is by no means restricted to this particular insect. 



■Turnip-flea, with wings e.Ypanded. 



