64 G. F. HILL. 



days the male was generally found clinging to the female, but copulation was not 

 again observed. The male died on the sixth day, and on the eighth day the female 

 was seen to have the proboscis deeply buried in the tissues of the bark, apparently 

 engaged in preparing a hole in which to insert an egg. Later in the day she was 

 attacked and crippled by small ants {Pheidole megacephala). On the following day 

 she was dissected, and an egg was found in the oviduct. Later two batches of six 

 couples each were confined on the bark of the same tree in a similar manner. Most 

 of the males died within ten days, and on 29th September there remained alive only 

 one female of one batch and three of the other. On the latter date the cages and their 

 contents were removed to fresh sites for further observation, and the bark previously 

 covered by the cages was carefully examined for eggs or larvae. Although the surface 

 showed numerous punctures, some of which extended to a depth of 3 mm., no trace 

 of eggs or larvae could be found. The reason for this apparent delayed oviposition 

 has not yet been determined, but it may be found to be due to refusal to oviposit in 

 captivity even under conditions so closely simulating nature. 



At noon on 8th September a wild female was observed with the proboscis inserted 

 in the bark to a depth of about 3 mm. At 5.30 p.m. the hole was found to be plugged 

 with comminuted bark, under which an egg lay 2 mm. from the surface. This egg 

 was removed in situ to the laboratory, where it hatched 7 days later. About this 

 time several other eggs were found in similar circumstances. 



The egg is a rounded oval measuring 0-528 mm. in width by 0-688 mm. in length, 

 pearly white in colour, with a very finely granulated surface. 



Larval Development. 



Upon hatching the young larvae tunnel into the bark, subsequently, and while 

 yet very small, boring into the sapwood, obliquely or horizontally at first, but always 

 horizontally sooner or later. The duration of the larval and pupal stages has not yet 

 been ascertained, but it is believed to total 12 months at least. Experiments designed 

 to determine these points, andalso the length of life of the perfect insects, are in progress. 



Appearance of Infested Trees. 



The earliest observed symptoms of infestation are pronounced withering of the 

 terminal twigs, followed by partial defoliation, the development of numerous adven- 

 titious tufts of foliage (Plate III), and the death of the secondary and, later, the main 

 branches. The cause of these conditions is not manifest until the perfect insects begin 

 to emerge from the dead or dying branches or, very rarely indeed, from branches in 

 which there is still a flow of sap. As a rule the injury caused by the larvae is such 

 that the branch is destroyed before the first beetles emerge. 



The bark of a heavily infested branch will be seen to be pierced by numerous 

 clean-cut holes (fig. 1) of various sizes, ranging from 1-5 mm. to 7 mm. in diameter, 

 the smallest of which, i.e., those up to about 2 mm. in diameter, are made by the adults 

 of Hymenopterous parasites which have in the larval stage destroyed the young 

 Euthyrrhinns larvae, the larger by adult weevils. The latter holes vary a good deal 

 in size in accordance with variations in the size of the adults, i.e., from 2 mm. to 6-5 

 mm. in width by 4-5 mm. to 12-5 mm. in length. The males are generally, if not 

 always, very much smaller than the females ; but this statement appears to be often 

 contradicted by the finding of pairs of approximately equal size in a copulatory 

 attitude. If, however, these pairs are dissected they will be found to be females. 



On the removal of the bark the sapwood shows a few shallow surface grooves made 

 by the young larvae before commencing their drive towards the heartwood, but more 

 often they bore straight in towards the centre without preliminary tunnelling. A 

 large proportion of the young larvae fail to penetrate deeper than 5 or 6 mm. before 



