88 



PROTRACTED DEVELOPMENT. 



From ray experience with this and other species I have become con- 

 vinced that cases of protracted development are not only not rare to a lim- 

 ited number of individuals of a brood, but seem to be normal, and hence 

 may be "part and parcel" of the "wise provisions of nature" for the 

 continuance of a species. 



A larva of Ephestia Jcuehniella that had been placed in a small vial 

 began spinning web May 9, but progressed very slowly, remaining 

 motionless, always head downward, when examined daily for a week. 

 Once or twice afterwards the larva was observed to have reversed its 

 position, resting for several days at a time head upward. June 5 it 

 was seen to have added a second coating of silk about double that first 

 deposited. July 6 it had resumed its old position of resting head down- 

 ward. It was always motionless, but wriggled when touched. The 

 work of observing this larva had become tiresome, as it had not under- 

 gone any change for at least two months. October 1 the moth was 

 found to have issued. It was living and slightly worn, showing that 

 it had bred out during the last of September. The weather having 

 been unseasonably hot during what must have been the pupal period, 

 the duration of this stage may be placed as nine days, from which the 

 quiescent larval period of this individual may be deducted as over five 

 months. Before transforming this larva had deserted the old web and 

 spun a new cocoon. The moth was of full size and not shriveled. 



Experiment in flour. — The eggs laid April 18 served for the deter- 

 mination of the egg period and for the late spring life cycle period iu 

 corn meal as just related. The newly hatched larvae were divided into 

 two portions, the second lot placed in wheat flour gave rather surprising 

 results, for whereas the meal fed larvae developed, as previously stated, 

 in fifty-two days, not a moth issued from the flour until August 10, one 

 hundred and fourteen days from the time of egg deposition. The flour 

 was very fine and must have been exceedingly dry. The corn meal was 

 fresh, yellow, of the best quality, and hygroscopic, which will explain 

 the great difference in the periods of the larva? feeding upon each. 



An apparently normal case. — From the same lot of eggs that had 

 begun to be deposited by a single female April 18 and placed in corn 

 meal, full-grown caterpillars to the number of 9 were observed at 

 rest at the top of the jar June 2. At the same time a cocoon was 

 observed in the meal, which gave out the first moth June 9. Many 

 more moths continued to issue from the meal, but were still maturing' 

 when the first moths from the larva3 that had spun up at the top of the 

 jar issued. These latter appeared July 9, or just one calendar month 

 later than the first lot, which is the period of the protracted develop- 

 ment in this second instance for four individuals. 



