TETEAlVrEROUS PLANT-BEETLES. 161 



The larvae are for the most part short, fleshy, convex or hump-backed 

 grubs, usually living upon the surface of the leaves upon which they 

 feed, often in company with the mature insects. They have six thoracic 

 legs, and usually a fleshy terminal proleg. Living exposed to the light 

 they differ from the great majority of Coleopterous larvse in being more 

 or less highly colored. Some of them have the singular habit of pro- 

 tecting themselves by a covering of their own excrement, which will be 

 described more fully in treating of the sub-family of Oassidides. But a 

 considerable proportion of them are internal feeders. Some are leaf- 

 miners ; others inhabit the roots of herbaceous plants; and the larvf© 

 of Donacia live concealed in the stems of water-plants, thus confirming 

 their afiBnity with the preceding wood-boring tribe. These last men- 

 tioned larvne exhibit a habit extremely rare amongst the Coleoptera, but 

 which we have seen to be possessed by a few of the Curculionidte, that of 

 enclosing themselves in silken cocoons, when about to change to the pupa 

 state. These cocoons are sometimes found fastened in a row to the 

 stems of the aquatic plants in which the larvae reside. Some phytopha- 

 gous larvae change to pupae, attached to the leaves, but many of them 

 go into the ground. 



Being, as their name implies, pre-eminently plant-eaters, this tribe of 

 beetles occupies a prominent place in practical entomology, on account 

 of the many species which are injurious to the agriculturalist. 4mong 

 these are the Striped cucumber-beetle, and its root-boring larvae; the 

 cabbage and turnip flea-beetles; the flea-beetle of the vine; and the 

 tortoise-beetles which feed upon the sweet potato. 



When danger threatens, the Chrysomelidae do not usually attempt 

 to escape either by running or flying, but, like the Curculiouidae, seek 

 safety by contracting their limbs and falling to the ground. 



With regard to the size of these insects, as compared with the Coleop- 

 tera in general, the same statement is applicable which we made above 

 in treating of the Curculiouidae, and the terms large and small must be 

 understood as being similarly modified ; that is to say, half of an inch, 

 which is about the medium length of beetles in general, is large when ap- 

 plied to the insects of these two families, quarter of an inch is medium, 

 and an eighth of an inch or less is small or very small. 



Family LXI. CHRYSOMELID^. 



This family, as here constituted, comprises the whole of the tribe of te- 

 tramerous plant-beetles. It is made up of several groups, some of which 

 are sufficiently distinct, whilst others are more closely allied, thus ren- 

 dering a natural classification of them indefinite, from the doubt whether 

 certain groups should, or should not, be raised to the rank of sub-fami- 

 —21 



