TETRAMEROUS PLANT-BEETLES. 161 



The larvrR are for the most part short, fleshy, convex or huinp-backe«l 

 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 tx) the light 

 they difler from the great majority of Coleopterous larva; 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 Cassidides. But a 

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

 n)iners ; others inhabit the roots of herbaceous jflants ; and the larvae 

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

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

 tioned larva' exhibit a habit extremely rare amongst the Coleoptera, but 

 which we have seen to be possessed b3' a few of the Curculionida;, 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 i)lants in which the larva3 reside. Some phytopha- 

 gous larvfe 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. A.mong 

 these are the Striped cucumber-beetle, and its root-boring larva3 ; the 

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

 tortoise-beetles which feed upon the sweet potato. 



AVhen danger threatens, the Chrysomelidiie do not usually attempt 

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

 safetj' 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 Curculionidoe, 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 mediunif 

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



Family LXI. C'lIRYSOMELID^. 



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 sufliciently 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- 

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