. Annals. Entomology. 19221 Larrimer: Delayed Emergence of Hessian Fly 179 It may be noticed that the crest of the pupation curve on October 11, did not reach one hundred, indicating that approx- imately forty per cent of the larvse did not pupate during the time covered by the graph and subsequent examinations proved that they passed the winter in the old summer stubble. During the spring of 1921, from pupation records made as previously explained, it was determined that pupation of these "hang-over" larvae began March 17 and was practically. Fig. Map indicating the approximate date
. Annals. Entomology. 19221 Larrimer: Delayed Emergence of Hessian Fly 179 It may be noticed that the crest of the pupation curve on October 11, did not reach one hundred, indicating that approx- imately forty per cent of the larvse did not pupate during the time covered by the graph and subsequent examinations proved that they passed the winter in the old summer stubble. During the spring of 1921, from pupation records made as previously explained, it was determined that pupation of these "hang-over" larvae began March 17 and was practically. Fig. Map indicating the approximate dates of emergence of the "late wave' of Hessian fly in October, 1920. completed by April 10. Emergence of adults from these pupae began March 29 and continued throughout the month of April. A very few healthy larvae failed to pupate, but these were so very hard to find in the field that further observation on them was not practicable. Pupariation is a term that it has been found convenient to apply to that activity by which the larvae of Hessian fly change to the flaxseed stage, as distinguished from actual pupation. Pupariation records were made on the larvae, offspring of the late wave, in order to determine the condition in which they entered and passed the winter. At frequent intervals 100. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Entomological Society of America. Baltimore [etc. ]
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