THE FAUNA OF THE CACAO FIELD 119 



for general infection. That the practical planter is not so 

 far wrong as was supposed, is now becoming apparent ; 

 but until the matter has been thoroughly worked out, it 

 would still be quite unwise to depart from the measures of 

 control which previous expert knowledge has laid down. 

 It is certain that pod heaps are breeding-places for fungi ; 

 and it is also certain that infection can take place from 

 such heaps, but until it is further confirmed that there 

 is no, or little, danger from such heaps, planters should 

 clearly adopt the recommendations of the expert pathol- 

 ogist. Our species appears near to Tyroglyphus hetero- 

 morpkus, Felt. (Bank's revision, U.S.D.A., 1906). 



No. 19. " Plant Lice." Aphis of species. — These are 

 green, red, or black fly, or blight, so common on all kinds 

 of plants. Where they occur on cacao they may be readily 

 controlled by naeans of sprays of any of the soap or rosin 

 washes, several formulae for which will appear in a later 

 page. They are said to assist in pollination. 



No. 20. "Pod Hopper" or "Cacao Bug" {Horiola 

 arquata and allied species) are commonly foimd in Trinidad 

 and other West Indian islands on the stems and pods of 

 young cacao. They are sucking insects, and do considerable 

 damage to the crop, by causing exudations from the pods 

 which assist the entry of parasitic fungi, and by the actual 

 extraction of sap from their immature tissues, which of 

 itself is sufficient to cause the fall of young pods. In their 

 nymph and adult stages these insects are often guarded 

 by stinging ants, which construct over the Cercopids 

 tunnels, for their protection, made up of mud pellets. 

 The ants feed upon certain exudations of the Horiola, in 

 the same manner as from those of the common Aphis, which 

 are known to allow themselves to be " milked by ants," and 

 thus obtain the name of " ant cows." The species carrying 

 out this process are believed to be Camponotus atriceps, 

 Sm., and Cryptourus atratus, L. A species of Azteka, a very 

 small ant, has been observed protecting Dactylopius calceo- 

 larice and " Mealy Bug " in like manner. The " Pod 

 Hopper " can be controlled by the use of rosin wash. 



