Important Cotton Insects of Central Peru

Abstract

During a six weeks investigation of cotton insect problems in the Canete Valley, located about 100 miles south of the city of Lima, in central Peru, no evidence was found of the existence in Peru of either the Mexican cotton boll weevil or the pink boll worm. The Peruvian square weevil was found in nearly all fields examined and ranged from sea level to an altitude of over 2,000 feet. This species attacks only small cotton squares and causes them to flare and fall to the ground as do the squares attacked by the boll weevil. The square weevil is a small species, adults measuring from 2.5 to 4 mm. in length. The color is light tan or brownish but the integument under the scale covering is brown. The adults are extremely active and shy and are hard to find in the field but the flaring and falling of squares betray their presence. Usually only six or eight punctured squares occur on a plant but sometimes as many as twenty-five were found, these being apparently the work of one female. The development requires some sixteen or eighteen days and the larvae and pupae in fallen squares appear to be quite resistant to heat and drought. It is not known whether the species can survive freezing temperature during its hibernation period. The most serious cotton pest in Peru seems to be a species of leaf worm. (Possibly more than one species is involved.) This species appears to be native and occurs abundantly every year, requiring usually three poison applications during the season. At least four generations of this leaf worm must occur. The observations made indicated a developmental period of from twenty-two to thirty days. The multiplication is rapid in spite of the presence of a number of species of predators and parasites. The usual method of control has been arsenate of lead or calcium arsenate sprays applied by knapsack spray pumps carried by Indian workmen. These spraying squads often numbering over 100 men, do nothing else for three months but spray for leaf worm control. Their work is very inefficient. Dusting has been started to replace the spraying and has given much better control of the worms with a very great saving in the time and labor of application. The climatic conditions and the topography of the irrigated val1eys are ideal for airplane dusting work and such work is being started this season in Peru. Other important insects include several species of small caterpillars which bore into the developing bolls. Their work is followed by the spread of fungus diseases which complete the destruction of the bolls. By this combined attack a damage of from 20% to 25% of the crop is frequently experienced.