. Elementary principles of agriculture; a text book for the common schools. s warm weather it requires about six weeks tomature a weevil from the egg, while, in cold weather, they multiply veryslowly. The egg-laying continuesover a consider-able period and, asit requires such ashort while to ma-ture a new brood,it is no wonderthat they are foundin such numbers ingrain stored forany considerabletime. It is esti-mated that, in thecourse of a season,they mature six ormore generations, amounting to 500 or more individualsfrom a single pair. 241. The Grain Moths do more damage to th
. Elementary principles of agriculture; a text book for the common schools. s warm weather it requires about six weeks tomature a weevil from the egg, while, in cold weather, they multiply veryslowly. The egg-laying continuesover a consider-able period and, asit requires such ashort while to ma-ture a new brood,it is no wonderthat they are foundin such numbers ingrain stored forany considerabletime. It is esti-mated that, in thecourse of a season,they mature six ormore generations, amounting to 500 or more individualsfrom a single pair. 241. The Grain Moths do more damage to the storedgrain than the weevils. The most common species isthe Angoumois grain moth, so named from the provinceof Angoumois, France. It attacks grain in the field aswell as in the bin. The adult somewhat resembles thecommon clothes moth. It is light gravish brown andabout a half-inch across when the wings are eggs are deposited in clusters of twenty to thirtyand require only about four to seven, or more, daysto hatch the caterpillars. The latter bore into the. Fig. 111. Granary weevil, a, adult; b, larva;c, pupa; d, rice weevil. All enlarged. AfterChittenden. Some Special Injurious Insects 175 grain, and, after feeding on the starchy matter for aboutthree weeks, form a thin silken cocoon, from which theadult moth emerges in a few days. About thirty-fiv^days are used in passing from egg to adult. Four to,possibly, eight broods mature during the year. Whengrain is stored in bulk, only the surface layers are in-fested. Both the weevils and moths are subject to attacksby parasites. 242. Preventing Injury to Stored Grain. To reducethe injury to stored grain, use is made of repellants likenapthalene (so-called moth balls), salt, air-slakedlime, and other substances which, while not poisonous,drive the insect out. A temperature of 125° Fahr. issufficient to kill weevils, though more than 150° be endured by dry grain without loss of ger-minatmg power. Treating th
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