TETRAMEROUS PLANT-BEETLES. 
161 
Tlie larvae are for tlie 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 larvae 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 sab-family of Cassidides. But a 
considerable proportion of them are internal feeders. Some are leaf- 
miners; others inhabit the roots of herbaceous plants ; and the larvae 
of Donacia live concealed in the stems of water-plants, thus confirming 
their affinity with the preceding wood-boring tribe. These last men- 
tioned larvae exhibit a habit extremely rare amongst the Coleoptera, but 
which we have seen to be possessed by a few of the Cureuliouidae, that of 
enclosing themselves in silken cocoons, when aboutto 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 larva; change to pupae, attached to the leaves, but many of them 
go into the ground. 
Being, as their name implies, pre-eminently plaut-eaters, this tribe of 
beetles occupies a prominent place in practical entomology, on account 
of the many species which are injurious to the agriculturalist. Among 
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 Chrysomelidse do not usually attempt 
to escape either by running or flying, but, like the Curculionidm, 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 Curculionidte, 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. CHTtYSOMELID^S. 
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 
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