496 



has been identified by Mr. R. E. Turner as Campsomeris tasmaniensis, 

 Sauss. , the true D. formosa not occurring south of Cairns. The cane- 

 grubs parasitised by both Campsomeris radvla and C. tasmaniensis 

 are cliiefiy those of L. albohirta, additional hosts being Anoplognathus 

 boisduvaU, Lepidiota freneJii, L. rothei and L. caudata. Those used 

 at the insectary during March for the propagation of these parasites 

 were third stage examples of L. albohirta. 



The method adopted consisted in confining digger parasites separately 

 in metal cages holding about 15 cubic inches of soil, the grubs with 

 attached eggs being removed morning and evening and placed in 

 shallow wooden trays containing cells formed of moist compacted soil. 

 A convenient size of tray was found to be 16 inches by 13 inches, 

 which allowed room for 60 cells, and when full, the trays were stacked 

 so that the bottom of one formed the roof of the one below, leaving 

 just enough room for the larvae to spin their cocoons. 



From data obtained in the field it has been proved that third-stage 

 larvae of L. frenchi, L. albohirta, and a few of L. rothei, derived from 

 eggs deposited in December 1916, have during the past sixteen 

 months been feeding in virgin soil on blady-grass and other cereals. 



Urich (F. W.). Thrips, Black Ants and other Insect Pests of Cacao 

 in Grenada, with a Note on Coconut Disease. — Rept. presented to 

 the Govt, of Grenada, Trinidad, 1918, 23 pp., 6 figs. 



Heliothrips (Selenothrips) rnbrocinctus occurs on every cacao estate 

 in Grenada, but is particularly abundant in the south and west. In 

 the author's opinion this is due to lack of shade on the western part 

 of the Island, and he considers that growers will have to choose between 

 more shade or more spraying to control the thrips. Cacao is most 

 severely injured in respect of the foliage, which frequently drops off, 

 but the pods are also affected, becoming discoloured so that it is 

 impossible to distinguish the ripe from the unripe ones. Fggs are 

 laid by the female in the tissues of young leaves, the incubation period 

 lasting 3 or 4 days. In cacao, oviposition occurs in pods that are 

 nearly mature. The larvae require about 9 days to develop, then 

 enter a pre-pupal state lasting. 24 hours, followed by a pupal period 

 lasting 48 hours. The females, which may live for several weeks, are 

 parthenogenetic for several generations, a few males occurring generally 

 at the end of the year. As the generations are continuous, the increase 

 of thrips is rapid ; other food-plants that are restricted to certain 

 seasons for putting out new leaves and thus form continuous breeding- 

 grounds are galba, hog plum, mango, guava, avocado, almond, mammee 

 apple, cashew and roses. New shoots on cacao appear at the beginning 

 of the rainy season and it is then that thrips begin to multiply on 

 the cacao trees, the maximum appearance being just after the heavy 

 rains of May and June. A certain degree of moisture seems to be 

 necessary for the development of thrips ; at the height of the dry 

 season they are at their lowest ebb, although the damage done by them 

 may be most apparent at that time. A table illustrates the seasonal 

 history. Thrips are naturally controlled to a certain extent by 

 heavy showers of rain and by excessive drought. In Grenada the 

 larva of a lace- wing fly and in Trinidad several species of Reduviid 

 bugs exercise some measure of control, but these do not confine 



