312 FAMILY CERAMBYCIDAE 



The Adult or Beetle Stage. — The insect commences to acquire its adult 

 form in November or December (this period will vary by a week or two), 

 and then passes several months resting in the pupal chamber, whilst its outer 

 parts harden and solidify. When they have done so, the beetle may, in 

 exceptional circumstances, bore its way out of the tree by gnawing a tunnel 

 straight to the outside through the wood. The insect does not, however, 

 usually leave the tree in this manner. It simply breaks the calcareous 

 partition made by the larva at the top of the pupal chamber and crawls up 

 the broad lar\'al tunnel in the wood and gnaws its way through the bark. 

 In the majority of cases this would appear to be its method of leaving 

 the white poplar trees. The beetles commence to appear from about the 

 beginning of May, and probably in April in years of mild winters and early 

 warm springs. Considerable numbers are still to be found in the first 

 part of June. The adult is much scarcer in July and August, though 

 individuals are said to continue to issue during these months. The 

 beetles pair soon after issuing, and the eggs are probably laid by the 

 female within a week to ten days afterwards. As has been already 

 mentioned, the eggs are deposited by the female in the sappy bark of the 

 tree, and to reach this, unless she can find any convenient wounds such 

 as are made by lopping branches, abrasions to the trunk during heavy 

 storms, etc., she bores down through the bark by means of her mandibles, 

 forming small saucer-shaped depressions, and, pushing her ovipositor 

 down into these, deposits a cluster of eggs. She probably repeats this 

 operation five or six times in different spots on a tree or trees. The egg- 

 laying as also the safe hatching out of the eggs is undoubtedly greatly 

 facilitated by (a) the presence of wounds on the trees, and (b) a warm dry 

 spring, since a greater number of the young larvae hatching from the fifty 

 eggs laid will reach full development. The male beetle dies after pairing 

 w^ith the female, and the latter after she has deposited all her eggs in the 

 trees. The dead bodies of the beetles are to be found lying at the foot 

 of the trees ; they are, however, probably quickly eaten up by small 

 rodents and other insectivorous mammals and also by birds, since even 

 towards the latter part of May (in 1905), when the beetles were issuing 

 in thousands from the trees in Quetta, dead insects were by no means 

 numerous. From the above notes on the life history it will he seen that 

 the insect takes two years to pass through its life history or life cycle : 

 a fortnight in the e^^ ; 5^- months feeding in the bast and sapwood 

 l)eneath the bark ; 6^ months in the wood in the interior of the tree ; 

 5 months as a pupa ; about the same time resting as a beetle in the pupal 

 chamber ; and 2 to 3 weeks in the beetle form outside the tree engaged 

 in pairing and egg-laying. When annoyed or frightened, the beetles, both 

 male and female, produce a squeaking sound by rubbing the posterior inner 

 dorsal edge of the prothorax over the anterior outer dorsal edge of the 

 mesothorax, the thorax being moved up and down in the vertical plane to 

 produce the sound. 



