Investigations on the relationship between pébrine disease of silkworm moths and their eclosion time during each, ripening of larvae and its combination were performed in the case of slightly infected moths from about 10% to 0.3%.
It was revealed that the percentage of diseased female moths always decreased in accordance with the retardation of eclosion date. The average percentage of diseased moths ripened earlier also was superior to those that followed.
The above phenomena, however, did not always fit well on the diseased male moths, although similar characteristics were generally recognized. For instance, in the male moths, there occurred almost always reverse infection percentage on intermediate days and in some case even the average value of the diseased moths derived from the ripened larvae on the following day exceeded those of the first. The average infection percentage of a lot between the female and the male also did not always agree each time.
The male moth, therefore, may not be suitable for the observation of pébrine control.