81 



Patterson (W. H.). Report of the Entomologist. — Gold Coast : Kept. 

 Agric. Dept. 1919, Accra, 1920, pp. 17-20. [Received 20th 

 December 1920.] 



Cacao pests were particularly troublesome in 1919, owing partly 

 to their remaining undisturbed for long periods during the war and also 

 to the abnormally dry season and the unusual distribution of rain during 

 the year. Important pests include the two bark-sappers, Sahlbergella 

 singularis, Hagl., and 5. theobromae, Dist. These suck the bark chiefly 

 of the woody shoots, preference being given to trees in rapid growth 

 from 2 to 5 years old. The food consists solely of the branches and 

 pods, the tissue of the shoot in the vicinity of each puncture being 

 killed down into the wood. During periods of dry weather the attacked 

 branches quickly wither and die. The only remedies possible are spray- 

 ing and hand-collection of the bugs, but neither of these is very 

 practicable, as each insect must be covered by the spray and hand- 

 picking is considered too tedious. The finding of 5. singidaris on 

 Berrya ammonilla, introduced from India, strengthens the view that 

 its food-plants are confined to Malvaceae and allied orders ; the only 

 previous food records are Eriodendron anfractuosnm and Gossypium 

 sp. Helopeltis bergrothi, Reut. (cacao mosquito) works in a similar 

 manner, but limits its attacks to soft green shoots and pods of all ages. 

 All the soft shoots may be continually killed, giving rise to die-back 

 disease. When very young pods are attacked they die, and thus the 

 yield is materially lessened, but older pods when punctured do not 

 suffer much. Heliothrips rubrocinctus, Giard (cacao thrips) caused 

 serious damage by feeding on the leaves and pods. The leaves fell 

 continually, so that a number of flushes of new foliage were produced 

 at the expense of the trees' vitality, and attacked pods failed to 

 change colour when ripe, and thus were either picked before maturity 

 or allowed to become over-developed. 



Coconuts are still badly infested with Archon centaurus, Burm. 

 (rhinoceros beetle) [R.A.E., A, viii, 9], and attention is drawn to the 

 necessity of co-operation in remedial measures and of clean sanitation 

 about houses and plantations, and to the advisability of passing legis- 

 lation to enforce action against this pest and of introducing parasites of 

 the larvae. Rhynchophorus phoenicis, F. (palm weevil) was occasionally 

 found attacking palms where fresh green leaves had been removed, 

 the wounds attracting the females for oviposition. Aspidiotus destructor 

 (coconut leaf scale) caused some yellowing of the foliage owing to the 

 decreased rainfall. 



The Hispid beetle, Coelaenomenodera elaeidis, Maul., defoliated 

 thousands of oil palms, which produced smaller bunches and individual 

 fruits with a thinner pericarp, and therefore less oil. The beetle seems 

 to be unchecked by parasites, and remedial measures are impracticable 

 [loc. cit.]. It is hoped that the succeeding rains will be more normal 

 in character, and that the unknown factors that exterminated this 

 pest in the Eastern Province during the rainy season of 1910 may 

 reappear. The weevil, Balanogastris colae, has been less injurious 

 on kola owing to the care with which the few fallen fruits that have 

 matured out of season, and in which the insects breed, have been 

 promptly removed. The essential point in the control of this pest is 

 the maintenance of a rigid close season. Losses to maize caused by 

 the maize stalk-borer, Sesamia sp., could be largely prevented if planters 

 promptly destroyed all young infested plants and all old stems as soon 

 as the first crop was harvested. 



