14 MONTHLY NOTES ON GRUBS AND OTHER CANE PESTS. 



were evidently the result of letting the insects stand too long before 

 they were used ; hence, decay had set in and ptomaine poison developed. 

 Beetles to be used for food of birds, and so forth, should be quickly 

 dried, and in this form they might be an important article of diet for 

 both fowls and insectivorous animals in public gardens. "We have had 

 a call for this kind of food during the last two years from zoological 

 gardens. 



Lepidiota Frenciii and Rothei, 



Both these beetles are still much in evidence ; the mating pairs 

 lianging on the low bushes every evening, indicating that they are 

 still emerging. After mating they feed for several days before they 

 are ready to deposit their eggs. 



In the fields (mentioned in the last report) infested with frenciii 

 ^rubs, conditions have improved since the continuous heavy rains; the 

 <;ane is greener and in some cases throwing out fresh roots. Extensive 

 diggings show that the number of grubs is materially less and that 

 many of them have been killed in the soil, for we often find them decaj^ed, 

 or, if near the surface, dried up. Of course, many are carried away by 

 ants soon after they die. Since these fields have been literally swarm- 

 ing with the parasitic wasps for a month or more, we naturally con- 

 clude that they have been responsible for much of this mortality among 

 the grubs. 



Experiments with poisons in this same field proved very encourag- 

 ing. Arsenate of soda mixed with megass and applied in a furrow along 

 the sides of infested stools apparently killed all the grubs, for none were 

 to be found in the treated section three weeks after application, though 

 they continued abundant in the remainder of the row, an average of 

 three being found under each stool. 



Experiments with repellents, on the other hand, have given but 

 negative results. Creosote sprayed on megass and placed in furrows 

 alongside the stools failed to retard the grubs, though the odour was 

 very strong in the soil after three weeks. Furthermore, any roots that 

 came in contact with the creosote fumes were killed, and the plants 

 showed a decided yellowing. 



Breeding op Parasites. 

 "Breeding experiments with Scoliid parasites have been attended 

 with marked success, and we are working out the life-history and meta- 

 morphosis of our two most useful species of digger-wasps, Didis for- 

 mosus and Campsomeris radula. 



"A specimen of the latter insect that was captured in a canefield 

 at Meringa last September lived for seventy-five days in confinement, 

 during which period it laid twenty-five eggs upon third-stage grubs of 

 JLepidiota frenchi. 



