118 THE CANADIAN ENTOMOLOGIST. 



The Cerambycids appear to have been in their origin scavengers, 

 rarely attacking sound wood ; but the larvie of many of them before reach- 

 ing full growth eat right into solid timber, while others appear to eke out 

 their existence by draining the afflux of sap to the part they have wounded ; 

 yet others again have deserted the forest tree that formed their ancestral 

 home and taken up their abode in the fruit trees of our orchards. The 

 larva? develop slowly, and must greatly reduce the vitality of the tree they 

 infest. They are exceedingly tenacious of life, and many instances are on 

 record to show that the larval stage is capable of enormous extension. 



The imago of Mojiohammus has been known to emerge from chairs 

 and tables years after the manufacture of the furniture. Mr. C. O. 

 Waterhouse, an English Naturalist, heard one of these larvse at work in a 

 boot-tree (an implement for stretching top boots) which he had in his 

 possession for 14 years; he then presented the implement to the Natural 

 History Museum at Kensington, where for six or seven years longer the 

 larva continued to saw wood. The entire absence of sap had of course 

 arrested the development of the larva, and it was unable to complete its 

 transformation, Sereno Watson, the American botanist, relates another 

 case (Packard, U, S. Ent. Comm., 1890, p. 689), that seems to prove the 

 life of one longicorn to have lasted 45 years. When you add to this 

 tenacity of life the larval obscurity which makes even detection difficult, 

 it will be seen how serious a pest the longicorns may and often do become. 

 The Chrysomelians, on the other hand, live openly on foliage, which 

 they devour as beetles no less than as larvae. The larval stage is short 

 and the insect, as a rule, helpless and easily destroyed. They more than 

 compensate, however, for their exposure to attack by their rapid breeding, 

 many genera producing two broods every season. There are 11 tribes of 

 the family in boreal America, all of them represented in Ontario. But 

 the great bulk of our Chrysomelidae belong to the four consecutive tribes — 

 Cryptocephaliiii^ Eiutiolpifii^ Chrysomeliiii and Galeriicini — the last of 

 these is far the greatest, and contains more genera and almost as many 

 species as the other three combined. Together these four tribes contain 

 more than two-thirds of the entire genera and species in the family. 



As, geologically, the woody fibred vegetation preceded the leafy and 

 succulent plants, it is probable that the Cerambycidae attained their great- 

 est development far earlier than the Chrysomelidae. But the two families 

 are undoubtedly closely akin, and the Donacias may be regarded, both in 

 form and in habit, as in many respects intermediate between some of the 

 less highly-specialized genera of Cerambycids and the Chrysomelids. 



