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THE AGRICULTURAL NEWS. 



September 2, 1911. 



INSECT NOTES. 



THE MANGO WEEVIL. 



The Bureau of Entoinolog}- of the United States 

 Department of Agriculture, has recently issued a Circu- 

 lar (No. 141, June 20, 1911) giving an account of the 

 inango weevil {Cry ptorhynch us onangi ferae) and the 

 injuries that it causes to mangoes. There is great dan- 

 ger that this insect may be introduced wherever mango 

 seeds are imported for planting, and though mangoes 

 are not grown from imported seeds to any extent, if at 

 all, in tlie West Indies, the very serious results likely 

 to follow the introduction of the mango weevil into 

 these islands render it desirable that all readers of the 

 Agricultural News should be in possession of the 

 known facts regarding it. Consequently, the circular 

 mentioned above is parti}' reproduced herewith. 



It may be of interest to mention that the mango 

 weevil belongs to the same genus as the -Jacobs or 

 Scarabee of the sweet potato {C. hatatae). Another 

 insect of this genus is common in St. Vincent as 

 a borer in cultivated crotons (Codlaeum spp.), and 

 still another was reported some years ago as a similar 

 pest in orange trees (Fig. 13) in Grenada (see Agricid 

 tural News, Vol. I, p. 280). A brief account of the 

 mango weevil in Hawaii has already been given in the 

 Agricultural News (see Vol. V, p. 90). 



Fig. 13. Oi!AN(iE Bai!K Weevil. 



Beetle, about natural size. Grub, one-half natural size. 



The most serious insect pest of the mango in oriental 

 countries is the inango weevil {Cryplm-hynrkus iiMnyiferae, 

 Fabr.) This weevil is related to the boll weevil, and this, 

 aside from its well-known destructive work on the mangoes, 

 is sufficient indication of its undesirability. It is probably of 

 Indian or at least of oriental origin, and has already obtained 

 foothold in most of the important mango-growing countries, 

 being carried readily with seed for planting. It now inhabits 

 all the mango regions bordering on the Indian Ocean and 

 adjacent islands, and occurs throughout the East Indies, 

 including the Philippines and other groups of South I'acific 

 islands. It has gained foothold similarly in South Africa 



and Madagascar and numerous other points. Fortunately, 

 this country [the United States] is so far free from this pest, 

 and if it can be kept out, the mango industrj' which it is 

 hoped to develop in Florida and perhaps in the other warmer 

 parts of this country can be given a very great advantage 

 over other mango-producing regions of the world. 



As has been indicated already, this mango pest belongs 

 to the weevil family. The egg is deposited in the fleshy part 

 of the fruit, and the young grub burrows at once into the 

 seed pod and develops in the seed to a pupa, and finally to 

 the adult weevil or beetle. The green mango soon heals up 

 over the egg slit, and there is very little, if any, exterior 

 indication of infestation. The weevil or beetle is about 

 |-inch long, and dark brown in colour. It remains in the 

 seed for somp time, and may thus be easily' distributed 

 with seed for planting, or with the ripened fruit. 



Protected as it is within the seed pod, and, in fact, with- 

 in the seed itself within the pod, it is not possible to destroy 

 it by fumigation with any certainty. The only means of 

 determining infestation is in opening the seed pod and remov- 

 ing the paper-like covering of the seed itself, when normally 

 the gnawing and excrement and discoloration due to the work 

 of the larvae and weevil can be noted. Therefore, all seeds 

 introduced for planting in this countr}-, in regions where 

 mangoes are grown, should be opened in this manner, and all 

 that indicate infestation shouM be burned. As a matter of 

 further security, all the apparently sound seeds should be 

 germinated in a box under a wire screen, so that any weevils 

 which may occur in seeds which show no visible sign of 

 infestation maj" be retained and destroyed. The danger is 

 particularly great where, as is now the case, mango seeds are 

 being imported for planting in regions in Florida where fruit- 

 ing mango trees occur. Where there are no mango trees, or 

 trees of fruiting age, the danger is perhaps negligible, as no 

 other food plant is known for the mango weevil. Still, if 

 large numbers of these weevils should be introduced and 

 liberated, they are long-lived, and might easily be carried on 

 railway trains to regions where they might find lodgment. 

 It is, therefore, desirable in any case to observe all the pre- 

 cautions indicated. 



It has already been stated that this mango weevil is the 

 principal enemy of the mango practically wherever this fruit 

 is grown. In the Hawaiian Islands, Mr. D. L. Van Dine, 

 formerly Entomologist of the Hawaii Agricultural Experiment 

 Station, reports that, during the first year of his examination, 

 he found 60 per cent, of the mangoes infested, and the fol- 

 lowing year from 80 to 90 per cent., in some instances iis 

 many as four larvae being foutid in a single seed. While the 

 mango weevil destroys, primarily, the seed of this fruit, it is 

 also believed by growers to hasten the maturity of infested 

 fruit, and thus to increase the percentage of fallen mangoes. 



Inasmuch as this in.sect pas.ses its entire development 

 within the seed, it is beyond the reach of insecticides and 

 fumigation, and the only remedy which the bureau is able to 

 advise to prevent it from becoming a pest in the United 

 States is to collect and destroy all the fallen or supposedly 

 infested mangoes. 



It is most urgently important no«-, however, for Florida 

 to keep this weevil out. Mango seeds are now probably being 

 imported into Florida by various growers, and the danger of 

 such importation should be thoroughly understood, and 

 whatever authority the State may have to prevent or control 

 such importations should be put in operation. 



