Dec. 2, 1920.] Agricultural Gazette of N.S.W. 867 



The presence of larvae in a stool may or may not be directly discernible. 

 This seems to depend largely on the degree of infestation. If the stool is 

 badly infested, the suckers show evidence of arrested growth and premature 

 dying, of the leaves. This, it must be remembered, can also be produced by 

 other agencies. On the other hand, a partially-infested stool may bear a 

 normally healthy appearance. 



How to Detect Infection. — On mere appearance there is no certainty 

 whether infestation is present or not, but where any of the foregoing 

 symptoms, however slight, are showing the presence or otherwise of the 

 beetle can be easily determined by the planter. The original parent bulb is 

 usually the centre of infection, so that the most advanced stage of attack 

 will be found in the stumps in the middle of the clump. These can be sliced 

 downward with an ordinary sheath knife, and if infested the tunnels and 

 larvae of the beetle can be readily seen, as in Plate II, Fig. 10. Suspected 

 suckers also can be cut off through the bulbs and sliced, when the tunnels 

 and sometimes the larvae are revealed. 



Description of Stages. 



The Adult. — In general appearance the adult beetle resembles the com- 

 mon grain bettle, except that the former is many times larger. Found in its 

 usual moist habitat (the decaying banana bulb) the beetle, except when 

 newly hatched, when it is reddish-brown, is of a uniform black colour; but 

 when dried, the body is covered with a thin incrustation which gives it a 

 greyish appearance. The whole body is thickly and evenly punctured, with 

 the wing covers or elytra bearing impressed lines of strias containing rows 

 of punctures. The elytra are slightly shortened, freely exposing the 

 pygidium, which is pubescent and covered with setigerous punctures. The 

 body divisions, head, thorax, and abdomen, are distinct. The head is small 

 and spherical, deeply imbedded in the tubular apex of the prothorax and 

 prolonged in front into the usual snout or rostrum. The latter is moderately 

 curved downward, thickened between the antennae, with the mouth parts 

 situated at the apex. The antennae are elbowed. The prothorax is long, 

 narrowing towards the apex, with a thin, irregular, smooth, medium, longi- 

 tudinal strip on the dorsal surface. The legs are stout, the femora thick- 

 ened at the distal end, the tibiae terminating in a hook and the tarsi four- 

 jointed. 



Length, 12 mm. Breadth at base of elytra, 4 mm. 



Between the sexes no marked variation in size occurs, nor is the size of 

 the rostrum, as suggested by Tryon, a reliable distinction. The sexes, how- 

 ever, can be easily differentiated by the first ventral abdominal segment of 

 the male (Plate II, Fig. 3) being more or less strongly impressed in the 

 middle, while in the female (Plate II, Fig. 5) it is flat or even slightly 

 convex. The rostrum also exhibits some sexual variation (Plate II, Figs. 2 

 and 4), but only in so far that the rostrum of the male is more coarsely 

 punctured, and the punctures, though becoming finer, extend almost to the 

 apex. In the female the apical half of the rostrum is practically smooth 

 (Plate I, Figs. 4 and 5). 



