THE LIFE-HISTORY OF EUTHYRRHIXUS MEDITABUNDUS, FABR. 



65 



they are overcome by parasitic Chalcids. The survivors penetrate much deeper — 

 i.e., from 30-35 mm. — ^and when nearly full-grown turn about so as to direct the head 

 outward. In this position they enlarge the burrow to one uniform diameter from its 

 base to near the cambium, the frass accumulated in the process being very tightly 

 packed behind so as to fill from 10-22 mm. of the burrow, in the remaining portion 

 of which pupation takes place. 



Fig. 1 . — Main branch of a mango tree after the emergence of the weevils. 



On emerging from the pupal stage the imago appears to undergo a rather long 

 developmental stage within the pupal chamber, during which the body hardens and 

 the insect becomes sexually mature. 



The operation of boring its way out through the thin layer of sapwood and the 

 bark which lies between the chamber and freedom is evidently a long and tedious 

 process, judging by the notches worn on the sides of the hole by the leg joints of the 

 toiling insect. 



Parasites. 



Early in August, when the beetles were first noticed to be plentiful, a species of 

 Chalcid wasp was frequently found in close association with them, or on adjacent 

 foliage. Selecting a branch from which Eiithyrrhinus were then emerging and which 

 showed, in addition to their exit holes, a few smaller holes in the bark, two pieces, each 

 about 2 feet in length, were sawn off and removed to a cage, where during the next few 

 weeks about a dozen of the Chalcids emerged. On examination it was found that these 

 insects had developed in holes about half an inch deep, which had been made by the 

 young weevil larvae prior to being parasitised. Mr. A. P. Dodd, to whom specimens 

 were submitted, informed me that, although known to him from the Cairns district, 

 they belong to a new species, a description of which, under the name Chalcis enthyrrhini, 

 appears below. A few weeks later several specimens of Thaumasnra curculionis, 

 Girault, were reared from the same branch and from the feeding-holes of young 

 larvae of the same host. About the same time both parasites were also captured on 

 (2416) E 



