THEIR RELATION TO PLANTS 



63 



tissue which 

 In the larval 



the usual exceptions of course, but really very few in 

 number. The common "May-beetle" or "June-bug" 

 may be selected as a good type and this, as an adult, 

 exemplifies the habits of the series in its voracious 

 feeding. Most of the beetles of this series feed in the 

 adult stage, and in almost all instances it is a direct 

 straightforward devouring of growing 

 does not endanger the life of the plant, 

 stage the species are known 

 as white-grubs and in this they 

 are much more dangerous since 

 they feed upon the roots, often 

 destroying the smaller plants 

 such as grasses, berries and the 

 like. The step from living to 

 dead vegetable matter is a very 

 short one and so we find here 

 also quite a number of feeders 

 on dead or even decaying 

 plants, which of course are not 

 among the direct plant enemies. 

 In that great series of Phy- 

 tophaga, which contains the 

 families Chrysomclidce or plant 



beetles, and Cerambycida; or long-horned beetles, we find 

 all the tarsi or feet apparently 4-jointed, the third joint 

 lobed or divided into distinct parts. This is a very char- 

 acteristic structure and almost always indicates a leaf- 

 feeder. Most of the adult beetles in the Chrysomelidae 

 feed very simply and openly on leaf tissue, devouring 

 without plan or aim except to get enough. Occasionally 

 we do get some characteristic bit of feeding like that 

 of some flea beetles which eat little round holes, or 

 make channels that render their work readily identi- 

 fiable. The larvae vary more in their habits and, while 



Fig. 24. — Tarsi of Coleoptcra: 

 a, normally 5 - jointed ; b, 4- 

 jointed;c, 4-jointed with 3rd joint 

 lobed; d, same from side: c & d 

 always indicate a plant-feeder. 



