HYLECOETUS OR LYMEXYLON DERMESTOIDES (l.). 1 93 



are smaller than the females, but there are other distinct 

 differences; the male is proportionately narrower and the 

 female broader; the wing-covers of the male are brownish 

 yellow but black towards the apex (sometimes all black), in 

 the female the wing-covers are brownish yellow and the breast 

 and eyes are black. A very characteristic feature of the male 

 is the presence of a tuft or fan-like projection on the second 

 joint of the maxillary palps. There is considerable variation 

 among the adults, some dwarf forms resulting from under- 

 feeding, but generally the male may be said to measure from 

 6 to 13 mm., and the female from 9 to 16 mm. 



Larva. — The larva of Hylecoetus (Plate XIV. Fig. 1) cannot 

 be confused with that of any other forest insect. When full 

 grown it measures from 15 to 24 mm., the largest I measured. 

 The head is smooth and is provided with strong gnawing 

 mandibles, but no antennae are present. The three joints of the 

 thorax are strong, especially the first, which is much enlarged 

 and arched, and has a coarsely granular horny plate on its 

 upper surface. Each joint of the thorax carries a pair of legs. 

 There are nine abdominal joints. A very characteristic feature 

 is the last joint of the body which is prolonged into a tail-like 

 process, forked at the tip and provided with two rows of 

 chitinous teeth which are directed slightly backwards. The 

 larval gallery is not widened all the way to the exterior, and 

 this tail is used for pushing the frass through the little hole 

 in the outer layer of bark. Galleries exposed by removing 

 the bark are immediately plugged by the larvae, but a narrow 

 passage is left through which the tail may be seen projecting 

 when bore-meal is being expelled. The colour of the larva 

 is whitish yellow. 



Pupa. — The pupa, which is found in the burrow made by the 

 larva, measures up to 14 mm. Its general form and appearance 

 can be seen in Fig. 2. There are spines, the apices of which are 

 turned forwards, on the upper surface of each segment of the 

 abdomen. These spines aid the pupa in retreating down the 

 gallery if molested. The wing-covers, wings, and legs are free, 

 i.e. are not glued down to the body. 



Life-history. — The generation is normally an annual one. 

 The adult beetles issued in May and June, and after pairing 

 the females, in my observations, laid their eggs in June and 

 July. The eggs are laid singly in crevices of the bark. In 



