INSECTS. 



195 



In the beetles the metamorphosis is more complete than in the 

 forms of insects already described. The larva has six pairs of feet, and 

 strong jaws. In its external appearance it maybe much like a worm, as 

 in the case of the wire-worms and cut-worms, which are such pests to the 

 farmers, or it may be shorter and more fleshy, like the grubs so familiar in 

 decaying wood. The pupa is much like the perfect insect; one can readily 

 trace in it all the features of the adult. In some there is a cocoon which 

 maybe constructed out of the surrounding material, or, in rare instances, 

 spun by the insect itself. 



From the economical standpoint beetles may be divided into three 

 groups: those which are directly injurious to human interests from their 

 feeding upon cultivated plants, or upon other things valued by man ; 

 second, those which have from the nature of their food but little influence 

 upon agriculture or the like ; and lastly, those which are directly beneficial 

 from the fact that they live either upon decaying animal or vegetable 

 matter, or upon other insects which are injurious. 



First of these beneficial forms are the lady-birds, with which all are 

 familiar. Their hemispherical, polished bodies and their bright colors 

 and pretty markings make them favorites with all. The only plausible 

 explanation of their common name is that it was applied out of compli- 

 ment to the beauty of the insect : from this standpoint it is certainly 

 deserved. The species of lady-birds are numerous, and may be found 

 climbing over the leaves of plants, especially those with conspicuous 

 flowers. They feed to some extent upon the pollen of the flowers, but 



Ng^^g^ 



/ 



Fig. 182. — Lady-birds (a, Coccinella trifasciata; b, C. 9-notata and pupa; c, d, e, larva, pupa, 



and adult of Hippodamia ; f, Chilocorus). 



this is but an item in their diet; for they are fond of small insects, espe- 

 cially the plant-lice that swarm upon certain plants, and which, unless 

 checked by these pretty beetles, would work extensive injury to the foliage. 

 It would be a tedious task to describe our various species, nor is such 

 a course desirable. Our cut illustrates four of the more common forms; 

 and most of the species are essentially similar, the variations being in the 

 number of spots, and the colors red, orange, and black predominating. 

 Somewhat similar in appearance to the lady-birds, but greatly different 



