546 



Plaxk (H. K). La Hormiga Arriera y los Medios para combatirla en 



las Huertas de Cacao del Ecuador, flhc Control of A tin <,pp. in 



the Cacao Plantations of Ecnador.] — Bol. Asoc. Agric. Ecuador, 



Guayaquil, i, no. 3, May 1921, 9 pp. [Received 23rd September 



1921.] 



With the exception of Monalonion alratum, the most important 



pests of cacao in Ecuador are the ants of the leaf-cutting, parasol, or 



fungus-growing species. The most common and the most injurious are 



Atta cephalotes and A. sexdens. The known facts of the history, 



biology and habits of these ants, and the remedial measures used 



against them are discussed. Very few natural enemies are known in 



Ecuador ; another species of ant is said to be predaceous on them, 



but cannot be considered to be in any way an adequate check. 



The remedies suggested include the use of repellents, such as 

 bichloride of mercury, and the destruction of the ants in their nests by 

 means of poisonous gases, such as sulphur dioxide or carbon bisulphide. 

 The quantities of the latter substance necessary for nests of various 

 sizes are as follows : — For a small nest, comprising only one or two 

 excavations, 30 to 50 cc. ; for nests measuring up to 5 ft. in diameter, 

 50 to 100 cc. ; for nests of 5 ft. diameter, 100 to 300 cc. ; for nests 

 larger than 5 ft., 300 to 600 cc. These are approximately the smallest 

 doses that are effective for the sizes indicated, and they should be 

 applied to the principal entrances, all the others having previously 

 been sealed up. In Panama, potassium or sodium cyanide has also 

 been used, with good results. 



Entomologia. — Bol. Asoc. Agric. Ecuador, Guayaquil, i, no. 3, May 

 1921, 2 pp. [Received 23rd September 1921.] 



Studies have been made of Monalonion atratuni, Dist., of which 

 M. dissimidatum is a synonym. This Capsid bug, known as the 

 " mosquilla," is the worst pest of cacao in Ecuador. Females in 

 captivit}^ lay 11 to 15 eggs, but in nature this number is doubled or 

 trebled. After about two weeks the n^Tuphs hatch ; they moult five 

 times before becoming adults, each stage lasting from two to five 

 days according to conditions of food and climate ; the adults generally 

 appear about one month after oviposition. Nicotine sulphate (Black- 

 leaf 40) 1 : 800 was found to kill the various stages of nymphs in 

 20 to 30 minutes, but did not apparently kill the eggs. The addition 

 of soap seemed to prevent the eggs from hatching. 



Leaf-cutting ants [Atta'] are very destructive in cacao plantations 

 [see preceding paper], and also to oranges, cotton or beans; un- 

 fortunately very little is done to destroy the nests, although this could 

 be effected with little expense, and the losses due to their presence 

 are considerable. Bananas are attacked by the banana weevil 

 [Cosmopolites sordidns]. Another weevil has been found in all stages 

 on palms, and is thought to be the cause of a very common form of 

 injury. 



De Stefani (T.). Diaspis pentagona e ProspaltcUa berlesei. — Alleva- 

 menti, Palermo, ii, no. 9, 1st vSeptember 1921, p. 291. 

 New mulberry groves are being planted in Sicily, and in view of this 

 renewal of the silk industry that once flourished in the island, it is 

 pointed out that no artificial measures need be taken against 

 Diaspis pentagona, provided its parasite, Prospaltella berlesei, is 

 encouraged. 



