In these closed leaves the larvae invariably commence feeding at the top of the leaf, soon causing the hood and closed lips of the leaf to collapse, thus effectually closing the tube and obviating the necessity for a ceiling web, which however, is sometimes spun some distance down the tube. The notch-cutting habit was not practiced in any of these immature leaves. As the larvae spin a carpet of silk wherever they go, this also aids in keeping the tube effectually sealed and in preventing the opening of the growing leaf. These hibernating larvae vary greatly in size, and molt at least once before the last larval stage is reached. After taking possession of a leaf, the lower portion of the tube fills up with corky frass particles, in which the cocoon is spun, the larva having previously cut two holes through the leaf wall, a large one above for the emergence of the moth,
and by burrowing down in the frass-filled tube, a small one some distance below the location chosen for the cocoon, this second hole being apparently for drainage; just above this drainage hole and between it and the cocoon, the tube is sealed with a lightly spun web, usually not two closely spun to retain the water. The small hole where the larva entered the leaf, unless obliterated by feeding of plugged with the accumulated frass, is usually closed with a web. The larva sometimes changes from the old leaf to a new one, and when this occurs just before pupation, unlike semicrocea, it eats enough of the new leaf to furnish frass and nibbled particles to render the cocoon opaque; usually, however, the cocoon is composed of the corky frass particles loosely held together with silk, and is built against one side of the tube, the leaf-wall on that side forming one wall of the cocoon.
…In ridingsii the pupal stage lasts ten to twelve days, emergence taking place in the daytime, usually between twelve and four o'clock. The pupa sometimes forces itself through itself through the top of the escape of the moth
. Pupation of the spring brood takes place from May 8th to May 20th, and the emergence of moths is complete by June 1st . The moths are extremely variable, some examples being suffused with black to the obliteration of all markings on the wings.