29 i 



wide valleys well watered by nunieroiis streams. L.fossator and its larva 

 are of large size and thus require more moisture than P. humilis ; 

 they are therefore found in the lowest parts of valleys and other 

 very damp situations. Both species fly in the evening and at night, 

 and at dawn they burrow into the ground ; if the latter be too hard, 

 the beetles are killed by the heat of the mid-day sun. They can live 

 for 3 months. The females lay about 20 eggs. "While these species 

 constitute the chief pests of sugar-cane, others of the same family, 

 such as Stenocrates laborator, F., also occur and do some injury. 



The larvae of L. fossator and P. huinilis appear to be able to live 

 for about 20 months. They remain underground at a depth of 6-8 

 inches, moult several times and then enter the nymphal stage, which 

 lasts about 12 days. Owing to the Avarmth of the Brazilian climate 

 the generations follow one another without a break. 



The larvae of L. fossator are more harmful than the adults ; both 

 stages attack the newly-planted cane-slips and kill old cane by feeding 

 on the roots. The adults of P. hiinnlis are more injurious than the 

 larvae, the latter scarcely attacking the slips or shoots. The adults 

 either bore into the slips from end to end or into the new shoots, 

 and the former injury makes re-planting necessary. As a rule neither 

 the adults nor the larvae of P. humilis are able to bore through the 

 hard bark of sugar-cane. In large plantations infestation with 

 L. fossator and P. humilis is not general, certain areas being foci of 

 infestation ; small plantations may be entirely destroyed. 



It is not possible to eradicate these pests, but proper measures, 

 based on the fact that infestation is limited to given points, should 

 prevent much economic loss. When the ground is being ploughed, 

 careful inspection will show the infested spots and these may be 

 marked with stakes. After an interval of about 30 days carbon 

 bisulphide may be applied by means of the Vermorel injector or Vernette 

 plough [R.A.E., A, ii, 256], or the ground may be flooded and re- 

 ploughed after draining. This second method W'ill interfere with 

 the cultural practices now used, so that disinfection with carbon 

 bisulphide is advised. The injector or special plough must be adjusted 

 to deliver 6 grams of carbon bisulphide. The plough is supplied by the 

 maker with a capacity up to 10 grams but that of the injector does not 

 normally exceed 6 grams, so that it should be ordered with a graduation 

 of 8 grams or over. The best plan would be to drill the holes in straight 

 lines so that the ground would be divided into squares with 19-inch 

 sides, and to inject 8 grams into each hole, but this is not usually 

 possible if the shps have already been planted. In this case it is 

 necessary to drill the holes in lines along the middle of the furrows 

 between the hues of slips, which are about 24 inches apart. The 

 dose of carbon bisulphide must be 6 grams in this case. Where circum- 

 stances allow it and the ground is of a permeable character flooding 

 for 48 hours may be resorted to. The adults of P. hmnilis that succeed 

 m escaping destruction by soil treatment may be captured by means 

 of hght-traps and a suitable model is described. It is provided with 

 a shade so that only those beetles that emerge from the surrounding 

 ground will be attracted. Lights that attract beetles from the neigh- 

 bouring woods are a danger. There is one fact relating to the larvae 

 of L. fossator and P. humilis that is very favourable to the sugar-cone 

 grower. During the heavy rains low-lying points become flooded and 



(684) ■" c2 



