326 FAMILY CERAMBYCIDAE 



down one side (fig. 218, b). The newly hatched grub is about an eighth of 

 an inch in length. A green tree free from the insect was felled on the 13th. It 

 was at once attacked (on the night of I3th-i4th) by the beetles, and on the 

 23rd was full of young larvae a few days old, whilst others were just hatch- 

 ing out. The largest found was a quarter of an inch in length, and probably 

 four to five days old (fig. 218, d). This larva was taken from the gallery 

 shown in fig. 219, i/. Others are shown in le. Unlike the larva of many 

 longicorn grubs, this one does not spend any time feeding in the bast, but 

 at once bores straight down through it to the sapwood and commences to 

 bore an irregular shallow gallery in this latter. This gallery is at first 

 narrow, and consists of two or more arms (fig. i^). It is entirely packed 

 with the wood excreta ejected by the larva, the only free space in it being 

 that occupied by the body of the grub. 



Life History of Larva. — The larva spends its whole life feeding in the 

 wood, remaining in the sapwood until it has attained full growth. It is to 

 be found in the larger roots, main stems, and in the larger branches of the 

 crown of the tree. It bores large irregular galleries here which are invariably 

 blocked with wood refuse. In these operations the cambium layer is usually 

 completely destroyed (cf. pi. xxiii). The grub has evidently a very rapid growth 

 when in favourable situations as regards food supply. This is proved by 

 the fact that larvae evidently hatched out during the year were found over an 

 inch in length early in May. In thedamp heat of the Assam climate eight to nine 

 months would appear to be the maximum time usually passed by the larva in 

 this stage of its existence, and the period may perhaps be much shorter, not 

 exceeding five months. Its work in the tree, performed at a greater rate, is 

 of a similar nature to that of the insect in the Central Provinces, and it 

 pupates in the same way by boring down into the heart-wood and eating out 

 a pupal chamber in the long axis of the tree. 



I came across several instances of trees felled in February 1906 which 

 contained larvae at least half-grown in the latter part of May. The explana- 

 tion is to be found in either of the two following suppositions : — 



(a) The beetles appear more than once in the year, winged beetles making 

 their appearance in the autumn months, although there is no true second 

 generation, the insect taking a year to pass from egg to beetle. 



(6) The grubs spend the cold weather hibernating in the pupal 

 chamber in the heart of the tree, the period of feeding being in the one 

 case from March to about November, by which time they are full-grown ; 

 in the other from June to March and March to June, when they would 

 pupate. As a matter of fact larvae were found in the heart of logs, or on 

 their way there, in the latter half of May. These may issue as beetles about 

 the middle of July, or perhaps later. 



Plates xxiii and iv show the work of the grubs in the sapwood and some 

 larvae and beetles in the pupal chambers in the heart-wood of a log. The 

 curious white calcareous coverings made by the larvae so as to close the 



