Of this total no less than $40,000,000 (8,000,000) is credited to a small beetle, the cotton boll weevil, and to two caterpillars.
The cotton boll weevil (Anthonomus grandis), a small grey weevil often called the Mexican boll weevil, is the most serious pest of cotton in the United States, where the damage done by it in 1907 was estimated at about £5,000,000.
No certain remedy is known for the destruction on a commercial scale of the boll weevil, but every effort has been made in the United States to check the advance of the insect, to ascertain and encourage its natural enemies, and to propagate races of cotton which resist its attacks.
The Indians in part of Guatemala raise cotton, although the boll weevil is abundant.
Mr Cook also found that the boll weevil was attacked, killed and eaten by an ant-like creature, the " kelep."
The boll worm is most destructive in the south-western states, where the damage done is said to vary from 2 to 60% of the crop. Taking a low average of 4%, the annual loss due to the pest is estimated at about 1 - 2,500,000, and it occupies second place amongst the serious cotton pests of the U.S.A. The boll worm is widely spread through the tropical and temperate zones.
The Egyptian boll worm (Earias insulana) is the most important insect pest in Egypt and occurs also in other parts of Africa.
Indian boll worms include the same species, and the closely related Earias fabia, which also occurs in Egypt.
" Boll rot," or "Anthracnose," is a disease which may at times be sufficiently serious to destroy from ro to 50% of the crop. The fungus which causes it (Colletotrichum gossypii) is closely related to one of the fungi attacking sugar-cane in various parts of the world.
The damage may be only slight, or the entire boll may ripen prematurely and become dry and dead.
Special interest attaches to experiments made in the United States to endeavour to raise races of cotton resistant to the boll weevil.
In some instances a slight difference in the shape, mode of opening, &c., of the boll prevents this, and accordingly seed is selected from bolls which suffer least under the particular adverse conditions.
The boll-weevil, preying on the cotton, is the most noxious of the insects.
See generally Franz Boll, Sphaera (Leipzig, 1903); also the bibliographies to ASTROLOGY and BABYLONIAN AND ASSYRIAN RELIGION.
See the Acta Sanctorum, Boll., 1st October; and the Register of Thomas de Cantilupe, with introduction by W.
Eine Inselstudie (Stuttgart, 1893); Edwin Muller, Die Insel Rugen (17th ed., Berlin, 1900); Schuster, Fuhrer durch die Insel Rugen (7th ed., Stettin, 1901); Boll, Die Insel Rugen (Schwerin, 1858); O.
The fruit or boll is round, containing five cells, each of which is again divided into two, thus forming ten divisions, each of which contains a single seed.
See Boll, Chronik der Vorderstadt Neubrandenburg (1875).