338 



FAMILY CERAMBYCIDAE 



disclosed the evidences of past attacks. Lower down in the green still-hving 

 portion of the stem grubs were found at work and also beetles just ready to 

 emerge. The insect would appear to be a pest of considerable importance, 

 since the grub feeds entirely in the bast layer and sapwood, destroying 

 the former when numerous. A dead tree examined showed the whole of 

 the bole from top to bottom covered with a mass of old larval galleries, 

 indicating that the major portion of the cambium layer of the tree had been 

 destroyed by the insects. It is not improbable that the trees are reduced 

 to the sickly condition best adapted for the attacks of this insect by being 

 partially strangled by the creepers which infest these forests. The insect 

 is also favoured by being able to lay in all newly felled trees and unbarked 

 tops left in the forest. 



The cause of death of the beetles found in the pupal chambers has not 

 been discovered, but the insect is apparently parasitized by the Ichneumon 

 fly described below. Methods of combating attacks of this pest are identical 

 with those described under H. spinicornis. 



Bracon sp. — The Bracon grub feeds upon the Dialcgcs larva as an 

 external or internal parasite, finally killing it. 



Cocoon. — Smoky grey, flat, elliptical in shape, consisting of 

 a \cry thin shining papery material. 



Fly. — Elongate, slender, shining orange- 

 Parasitic Insect. red. Head dark red with black rather 



short antennaeand a long curved ovi- 

 positor longer than the total lengthof the insect ; the wings are 

 membranous, slightly longer than the insect ; anal tips with smoky 

 l^ands and upper wings with three black spots, two on the exterior 

 edge of the upper half and one on the inner edge in a line with the 

 lower spot. Length, 18.2 mm. 



Life History. — This Bracon would appear to 

 lay its eggs in the neighbourhood of those of the 

 longicorn or on the grub itself after it has hatched 

 out. The parasite feeds upon the latter, but does not 

 apparently eventually kill it until it has eaten out the 

 pupal chamber and closed it over with the calcareous 

 covering. The parasite then leaves its host, the 



latter shrivelling up, and spins the papery elliptical cocoon and pupates 

 inside it. I do not yet know at what period or periods the fly issues, since 

 I have only taken dead flies in situ in the pupal chamber. They were taken 

 from pupal chambers in the tree in which the dead beetles were discovered. 



Further investigation into the life history of this insect is required. 

 How many life-cycles the Ichneumon passes through during the year, 

 how its grub feeds upon the longicorn one, how the fly gets out of the 

 closed pupal chamber, and its abundance in the forest, are some of the 

 points which present themselves for decision. 



Fig. 226. 



Bracon sp. Cocoon 



and Fly. Parasiticon 



Dialeges paupe7\ 



Assam. 



