FOOD PLANTS. 31 



FOOD PLANTS OF THE BOLL WEEVIL. 1 



The careful investigations of Mr. E. A. Schwarz in Guatemala, 

 Mexico, and Cuba have convinced him that the original food plants 

 of the boll weevil are the tree cottons of those countries. One of 

 these species has the seeds adhering together in a mass and is called 

 "kidney" cotton from the shape of this mass. The other has seeds 

 separated as in Upland cotton of the United States and is probably 

 the Gossypium brasiliense of botanists. The former appears to be 

 the more ancient form and presumably is the species upon which the 

 weevil originally subsisted. Cotton is now rarely cultivated in Cuba, 

 but the practically wild tree cottons are found throughout the island, 

 and on these the boll weevil is generally to be found, although in 

 very small numbers. There are, however, frequently found through- 

 out the island isolated plants which are not infested. The areas of 

 cultivation of cotton in Guatemala are extremely isolated, but the 

 presence of tree cotton perpetuates the weevil and gives it a rather 

 general distribution. In Mexico the principal regions of cotton 

 growth are represented by narrow belts along the two coasts and a 

 large area in the north-central portion known as the "Laguna." 

 Tree cotton probably serves to continue the boll weevil's activity in 

 many parts of Mexico where cotton is not cultivated. It is impos- 

 sible to decide whether the boll weevil originated in Cuba or in 

 Central America, as it occurs in practically the same condition in 

 both places. It is, however, practically certain that the insect has 

 attacked the cotton plant from antiquity. In fact, there is nothing 

 to indicate that it ever had any other food plant. 



The question of the possibility that the boll weevil may feed upon 

 some plant other than cotton is one of importance. As an illustration 

 we may state that as long as cotton is extensively produced in any 

 given region there is comparatively little danger, but if a certain 

 region should forego the planting of cotton for a period of years in 

 order to escape boll-weevil injury and then resume its cultivation, it 

 is apparent that all efforts would fail if the boll weevil could in the 

 meanwhile exist on other native plants. 



It is a well-known fact that insects which have few food plants 

 usually confine their attacks to closely related plants belonging to the 

 same botanical family or even genus. The native plants most closely 

 allied to cotton in the regions so far infested are the various species of 

 Hibiscus and the trailing mallows of the genus Callirrhoe. Careful 

 tests have been made with these plants and with many unrelated 

 plants, both as to their powers of sustaining life and the inducements 

 offered for oviposition. Six species of Hibiscus, namely, esculentus, 

 vesicarius, manihot, moscJieutos, militaris, and africanus, have been 

 tested to ascertain how long the weevil could live on them and whether 

 it would oviposit in the fruit. In experiments conducted by Dr. W. E. 

 Hinds hibernated weevils starved in an average time of about four 

 days with leaves of either Hibiscus esculentus or H. militaris. Weevils 



1 There has recently been discovered by Prof. C. H. T. Townsend another serious cotton pest, Antho- 

 nomus vestitus Boheman, which we may designate as the Peruvian cotton square weevil, as it is not at pres- 

 ent known outside of Peru and Ecuador. Prof. C. S. Banks has also discovered in the Philippine Islands 

 a weevil feeding in cotton flowers which may be known as the Philippine cotton flower weevil. This species 

 has been described as Ecthetopyga gossypii Pierce. The coffee-bean weevil, A rascerus fascicviatusDeGeer, 

 frequently breeds in old dried cotton bolls, and the cowpea pod weevil, Chalcodermus xneus Boheman, 

 breeds occasionally in fresh cotton squares in fields of cotton following cowpeas. On account of the exist- 

 ence of these other square and boll weevils it is still necessary to retain the original name Mexican cot- 

 ton boll weevil for Anthonomus grandis Boheman. 



