THE FAUNA OF THE CACAO FIELD 115 



Professor L. O. Howard, who reports that " It is known 

 to live in all sorts of seeds, fruit and cotton bolls that have 

 been infested by other insects, and in which various species 

 of moulds are growing. A very closely allied species, 

 Brachytarsus variegatus, lives in North America exclusively 

 on ' smuts,' so injurious to cultivated gramineous plants." 

 Our observations in field and laboratory show that our 

 species, Arcecerus fasciculattis, De Geer, also feeds upon a 

 fungus or smut, viz., Diplodia cacaoicola, P. Henn, which 

 causes the brown rot of the cacao pod, and eventually 

 clears such material of all living spores. This has a very 

 important bearing upon the hygiene of the cacao field, for 

 it shows that the danger of infection is largely controlled 

 by the work of these beetles. Planters have long held 

 the opinion that heaps of shells or rotten pods do not 

 always spread disease, and the reason is shown to be the 

 presence of natural checks, such as has been found in the 

 beetle which has now been brought to notice, in conjunc- 

 tion with other insects having similar habits. It would, 

 however, be quite unwise for the planter to rely absolutely 

 upon such checks ; he should follow the procedure laid 

 down for his guidance by mycological and entomological 

 experts, using the means laid down to the best advantage 

 guided by his own knowledge of existing conditions. 



Brachyomas tuber culatus, Chevr., Anchonus suillus, Fabr. 

 and Dicornis mixtus, Fabr., are small weevils which are 

 also recorded as found in dead pods, large and small, and 

 probably act as scavengers and possibly (as is also the 

 case with Arcecerus) as distributors of fungus spores. 

 Our observations on the point in laboratory experiments 

 how that they destroy millions of spores, while they can 

 only distribute the few that attach themselves to the 

 outside of their bodies which, though not a quantity to be 

 neglected, are comparatively of small importance. Studies 

 in a direction which insures a correct knowledge of the life 

 history of the jungi and insecta which frequent cacao 

 estates must be fruitful of discoveries for many years to 

 come, for it is now fairly clear that were it not for the 



