=n Renae ee Cae rab Gpates Pat ee a Rr a es phen ay etn Batic ye Dpto Ve -tantatonsile jn Maths Sp aie ren Menthe pehin Thnt o!s Yas e fnNim Oor ; : ; ‘ et eS mr Te A Te A (Fe Mine tie. he Me! oe YS tee ce PE MP ns acne 4 a Ae es Ne Aes wipe seonrbacinc ta Pra sate thee rte AA ER EN! i Ae 0 tpt thn Rene rnle hae to Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. T \ ees u = . [ —aae, —\\ —— Po/ ee ee 4 cotton fields of south - Texas. The investi- # _ visited Texasin May CIRCULAR No. 14, SECOND SERIES. (REVISION OF No. 6.) United States Department of Agriculture, DIVISION OF ENTOMOLOGY. THE MEXICAN COTTON-BOLL WEEVIL. (Anthonomus grandis Bol.) SCOPE OF THE CIRCULAR. Circular No. 6 was published in April, 1895, and contained a brief report of the observations made up to that time, and the conclusions based on those observations, concerning the Mexican cotton-boll weevil, an insect of Central American origin which, during 1894, attracted considera- ble attention in the gation was continued during the summer, fall, and early winter of 1895, especially by Mr. Sehwarz, who and June and again from October to De- cember, and by Mr. Se ast Townsend, who was £1¢-1.—Anthonomus grandis: a, adult beetle; >, pupa; ¢, larva—all stationed in theState ee during the greater part of the summer. The writer went to Texas in December, and in company with Mr. Schwarz carefully studied the condition of affairs at that season and talked with many prominent cotton growers. The object of the present circular is to lay before cot- ton planters the results of this supplementary investigation. In order to make it complete in itself, such facts as are needed are repeated from Circular No. 6. GENERAL APPEARANCE AND METHOD OF WORK. This insect is a small, grayish weevil, of the shape and general appearance shown in fig. 1, a, and measuring a little less than a quar- ter of an inch in length. It is found in the cotton fields throughout the season, puncturing and laying its eggs in the squares and bolls. . The larvee, of the shape and appearance shown at fig. 1, c, and measur- 1 2 ing a little over three-eighths of an inch in length when full grown, live within the buds and bolls and feed upon their interior substance. The squares attacked usually drop, but most of the damaged bolls remain upon the plant and become stunted or dwarfed, except late in the season, when they either dry or rot. DISTRIBUTION. This insect through its ravages caused the abandonment of cotton eulture around Monclova, Mexico, about 1862. Two or three years ago LEGEND e... ACTUAL OCCURRENCES, 1895. _o..-POINTS EXAMINED WHERE NO WEEVILS WERE FOUND. pe lag 14 } J Fic. 2.—Map showing distribution of the Mexican cotton-boll weevil. cotton was again planted in that vicinity, but the weevil immediately reappeared and destroyed the crop. At Matamoras the weevil was noticed eight or ten years ago. About 1893 it crossed the river at Brownsville, and in 1894 was noticed in the country around San Diego, Alice, and Beeville. At the close of the season of 1894 the insect occu- pied a territory extending to the north a little beyond Beeville, a few miles to the east of that point, and southwest to the neighborhood ot Realitos, on the National Mexican Railway. The greatest damage seems to have been done along the lower Nueces River. During 1895, and particularly in the latter part of the season, it extended its range to a considerable extent. Toward the east it was found in moderate 3 abundance along the valley of the Guadaloupe River at Victoria, Thomaston, and Cuero. North of its old range it extended to Kenedy, Floresville, and many points in the country lying between the latter place and Cuero. A single field was found near San Antonio which contained weevils in large numbers, and in the same way a single field was found far to the east at Wharton in which the weevils had appeared late in the season. The exact localities where the insect was found during 1895 are indicated on the accompanying map. NATURAL HISTORY AND HABITS. The insect passes the winter in the weevil state. It can be found on the cotton plant until late in December, and, in fact, as long as any portion of the plant is green. It is found most abundantly in the early winter hidden between the in- volucre and the boll, and later it frequently works its way down into the dry and open bolls. All the specimens found by Mr. Schwarz in such situations in the late spring of 1895 were dead; but Mr. Townsend found a few living in March. The dry boll is probably not a fre- quently successful hibernating place. Judge 8. G. Borden, of Sharpsburg, however, writing under date of January 27, 1896, states that the weevil at that time was being found nearly every (lay in the dry bolls; but this statement lacks the sig- nificance which it might other- ,,., ; ‘ eer Bey ie : = : G.3.—a, newly hatched larva in young. square; 2, wise have had as bearing on nearly full-grown larva in situ; c, pupain young boll the question of hibernation from Picked from ground. the fact that no heavy frost had probably occurred up to that time at Sharpsburg. With the cutting of the plants or with the rotting or drying of the bolls as a result of frost, the adult weevils leave the plant and seek shelter under rubbish at the surface of the ground, or among weeds and trash at the margin of the fields. Here they remain until the warm days of spring, when they fly to the first buds on such volunteer plants aS may come up in the neighborhood. They feed on these and lay their eggs on the early squares, and one, or perhaps two, generations are developed in such situatious, the number depending upon the character of the season and the date of cotton planting. By the time the planted cotton has grown high enough to produce squares the weevils have become more numerous, and those which have developed from the gen- eration on volunteer cotton attack the planted cotton, and through their punctures, either for feeding or egg-laying, cause a wholesale shedding of the young squares. It seems to be an almost invariable rule that a square in which a weevil has laid an egg drops to the ground as a result of the work of the larva; in the square on the ground the larva reaches full growth, transforms to pupa, and issues eventually as a beetle, the time occupied in this round approximating four weeks. Later, as the bolls form, the weevils attack them also and lay their m= ik 4 eggs in them, and the lurve develop in the interior just as with the squares. The bolls, however, do not drop. Figs. .3, a, and 3, 6, show the larve in the squares, and fig. 3, ¢, shows a young boll cut open and the pupa in its customary position. 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