Cotton Leaf Perforator (Bucculatrix thurberiella)

Cotton leaf perforator is a minor pest of cotton in most growing areas. In hot dry locations, such as Arizona, California, New Mexico and Texas, it can cause significant damage. The potential for damage increases with repeated pesticide use due to the loss of natural controls.

Early instars feed in mines in leaf tissue. This feeding behavior continues through the third instar. As larvae molt to the fourth instar, they leave the mine and feed freely on leaf tissue. These older larvae cause small holes and can skeletonize an entire leaf. 

Severe infestations of cotton leaf perforator can impact boll maturation and development. Defoliation can stop the growth of the plants, slowing or stopping the maturation process.

Eggs are oviposited singly on the underside of leaf tissue. Early instars, 1 to 3, feed in randomly shaped mines. Fourth instar larvae feed freely on leaf tissue. A resting stage occurs between the fourth and fifth instar. This stage is easily recognized by its characteristic horseshoe shape. It is usually located on the underside of the leaf. Upon emergence from the resting stage, the fifth instar continues to feed freely on leaf tissue. Mature larvae spin a cocoon on plant parts.

The adult moth is small (about 1/2 inch), slender and white. Black markings may be present on the forewings. The larvae is dull green with black spots with white tubercles in two rows along its back. At maturity the larvae will be approximately 1/2 inch long. Cocoons are slender with ribs and about 1/2 inch long also.