FAMILY CURCULIONIDAE 395 



to extremes of heat and cold, have several jrenerations or life-c\-cles in the 

 3'ear, and in some instances wonld appear to continue the succession in 

 a particular tree until the tree has been killed. If the sustenance afforded 

 by the tree, i.e. the green-bast layer, has all been removed just before the 

 winter season, the mature beetles appear to hibernate till the spring before 

 leaving the tree. If the attack on the tree is not complete the beetles 

 apparently couple even in the late autumn and earh' winter, and eggs are 

 laid. This habit seems to be common at elevations below about 3,000 ft. 

 in mountainous regions. These bark-feeding forms pupate either in the 

 sapwood or thick bark of the trees they infest. Other species confine their 

 attacks to the soft succulent shoots and twigs of the trees, the grubs eating 

 out the heart and killing the shoot. Instances of this method of attack are 

 best seen in the case of bamboos infested by particular species of weevils. 

 The insect usually lays its eggs near the upper part of the growing shoot of 

 the bamboo, and not infrequently chooses for her purpose a young bamboo 

 in its first year of growth. The grub tunnels out the heart of the growing 

 shoot, eventually pupating near the top. This top dries and falls to the 

 ground, the pupa remaining in it till the beetle has matured. This is a very 

 common form of attack by species of the genus Cyrtotrachclus (p. 440). 

 Another genus — -and there may be more than one — ^girdles young seedlings 

 and lays its eggs in the part above the girdle, the grubs feeding on the 

 slowly decaying tissues of this portion. 



Other genera, again, appear to confine their attacks to the seeds and 

 fruits of trees. The eggs are laid either in the flower or more commonly in 

 the young fruit, the weevil making a small hole in one side of it arid inserting 

 one or more eggs. The young grubs feed inside the growing seed or fruit, 

 eventually partially or completely hollowing it out. The dead fruit or seed 

 then falls to the ground, the grub or grubs either pupating inside it or 

 tunnelling out of it into the ground and pupating there. This is the life 

 history of probably a considerable number of the seed-eating weevils of 

 the forests, of which species o{ Alcidcs and Culaiidra furnish examples. 



The forester will rarely find the weevils which are reared inside the tree 

 or in the seed on the wing in the forest. They are mostlv nocturnal insects, 

 issuing when mature at night and flying off in search of fresh trees to ovi- 

 posit in or pair upon. In fact, for the forester, broadly speaking, the weevils 

 divide themselves into two divisions: (i) The nocturnal group, containing 

 serious pests infesting the bast of the main stem of the tree, and often 

 killing it or infesting and destroying the seed, and thus restricting, or for 

 one or more seasons entirely preventing, natural regeneration of the species. 

 (2) The diurnal division, the weevils which are to be found on the wing 

 in the forest during the daytime, feeding upon the leaves or flowers or 

 ringing or feeding on the green shoots. These beetles are usually brighter 

 in colour than the nocturnal ones. The group includes a large number of 

 species belonging to such well-known genera as Mylloccrna, Apodenis, Rhyn- 

 chitcs, Cyrtcpistonius, etc. 



