FAMILY SCOLYTIDAE 591 



area posteriorly smooth, shining, and finely pitted. Sparsely clothed with long yellow hairs 

 anteriorly. Elytra not wider than thorax, not quite twice as long, moderately convex, sides 

 straight to apical declivity, thence rather sharply constricted to apex ; surface dull with 

 feebly impressed rows of small punctures, the sutural striae more defined apically ; the de- 

 clivity moderate, set with small spiky prominences and clothed with a sparse long yellow 

 pubescence. Under-surface dark brown, abdominal segments punctate, with a spiny seta in 

 each puncture. Antennae and legs brown, shining. Length, 5.4 mm. to 5.8 mm. PI. Ix, 

 .figs. I and i a, shows this beetle, and fig. i b the borings in sal wood. 



Larva. Short, thick, white, but slightly curved, legless. Body corrugated. Length, 

 5.8 mm. 



Pupa. Short, thick, whitish yellow, having a resemblance to the beetle. 



The Xyleborus, which is the largest of the scolytid borers at present 



known as infesting the sal-tree, bores a single tunnel down 



Life History. through the bark into the sapwood. This is probably 



the work of the male. It goes in for about half an inch. 



At the end the insect hollows out a pairing-chamber. Two females are 

 apparently fertilized here by the male, or possibly sometimes three. After 

 pairing, each female tunnels away at an angle from the pairing-chamber, 

 either to the right or left, or if there are three females the third will go 

 directly downwards. In the gallery of a female carried to the right which 

 was examined on 20 May I took out, about two inches down, two pupae 

 and three nearly mature beetles (males and females). They were all in the 

 one gallery, to which there were no offshoots, and had a diameter equal to 

 that of the tunnel in which they closely fitted. As there \vere no offshoots 

 to the egg-tunnel nor any indication of the grubs having lived upon \vood, 

 it is probable that they belong to the class of ambrosia feeders and live upon 

 fungous growths lining the walls of the tunnels. The question arises, Are 

 the pupae and nearly mature beetles found in the wood in the latter part 

 of May those of the first generation of the year ? I think this possible. 

 Beetles w r ere also found tunnelling into newly felled trees within four days 

 of the latter being cut, evidently with the object of pairing and egg-laying. 

 It is thus probable that there are at least two, if not more, generations in 

 the year. 



The beetle itself bores down into living green wood of standing trees, 



which is a peculiar habit (pi. Ix, fig. i b). It probably 



^nTthe Forest. on b 7 infests sickly trees with stag-headed tops, but it is 



never found in the dead parts of the tree. Several green 



standing trees infested were examined. The dead tops invariably showed 

 that they had been tunnelled into in previous years by the beetle. Below 

 the dead parts near the junction of the old dead and the live green wood 

 it will be found at work. The beetle ruins the timber of the tree when 

 very numerous. 



