198 



NATURAL HISTORY. 



and three black stripes on the wing-covers. It can be seen in numbers 

 around the cucumber, squash, and other similar plants. 



The flea-beetles, which derive their common name from their jumping 

 powers, are also leaf-eaters, and one polished steel-blue species is a serious 

 pest on the grape, eating the buds as well as the leaves ; another feeds on 

 the cucumber and potato, while a third infests fields of turnips. 



Another type of leaf-eating beetles has received no common name, and 

 so, perforce, we must use the term under which it figures in science, — 

 Donacia. The species of this genus live on aquatic plants, the larvae 

 beneath the surface. One species which occurs in Europe has a most pecu- 

 liar way of obtaining the air necessary for respiration while beneath the 

 water. With its jaws it gnaws a hole in the stem of one of the aquatic 

 plants, and sticks the tip of its abdomen into the opening. On the tip 

 of the abdomen are hooks which serve to hold the larva fast : but they 

 have another purpose as well. Each of the, hooks is traversed by one of 

 the air-tubes of the larva, and so these hooks are breathing-organs as well 

 as anchors. In the tissues of the plant there is a considerable amount of 

 air, and this furnishes the oxygen necessary for respiration. 



There is but one of the leaf-eating beetles which has any value ; and 

 this a brilliant bronze-green species, with a very hard body, which is some- 

 times set in gold and used as jewelry. The species is very abundant in 

 South America, and specimens can frequently be bought in our own mar- 

 kets for twenty-five cents apiece. 



The long-horn beetles receive their common name from the long antennae 

 with which most of the species are provided. Like the leaf -cutters they 



Fig. 185.— Apple-tree borer (Leio- 

 pu8), one of the 'long-horn 



Fig. 18G. — Common apple-tree borer (Saperda) : larva, pupa, 



and adult. 



are to be classed among the injurious forms; but these do most of their 

 damage by boring during the larval state in the interior of plants and 

 Many of the species are very beautiful, and the group is a favorite 

 one with collectors. 



One of the best known of the long-horns is the apple-tree borer, a 

 nearly cylindrical beetle, about three-quarters of an inch in length. It is 



