. Bulletin of the Department of Agriculture. Agriculture. THE CHICKEN MITE. engorged, and is now bright red, oAving to the ingested blood showing through the skin. The measurements of the mite (average of five) at this stage are: Length, 568 microns (abdomen only); width, microns; thickness (average of three), 266 microns. After a period of somewhat less than 24 hours the first-stage nymph molts to the second stage. The average mean temperature during the period when the molting was observed was ° F. THE SECOND-STAGE NYMPH. The second-stage nymph, like the preceding stage, requi
. Bulletin of the Department of Agriculture. Agriculture. THE CHICKEN MITE. engorged, and is now bright red, oAving to the ingested blood showing through the skin. The measurements of the mite (average of five) at this stage are: Length, 568 microns (abdomen only); width, microns; thickness (average of three), 266 microns. After a period of somewhat less than 24 hours the first-stage nymph molts to the second stage. The average mean temperature during the period when the molting was observed was ° F. THE SECOND-STAGE NYMPH. The second-stage nymph, like the preceding stage, requires a short period of rest to harden the integument. As soon as the nymph becomes active it is ready to feed. Some authors have said that the mite takes long periods of rest. The writer finds that when such rest periods are taken it is from^ force of circumstances and not from desire on the part of the mite. The mite before feeding measures (average of four) microns in length and mi- crons in width. After feeding, the mite meas- ures microns in length by microns in width (average of 10). The second-stage nymphs molt to adults (fig. 1). This is the rule, although there may be some nymphs which undergo an additional molt before reaching the adult stage. The writer found one mite which apparently had three nymphal stages. A single instance, however, can hardly be accepted as sufficient evidence for making an exception to the rule. THE ADULT. As soon as the males crawl out of their nymphal skin they rest a short time, and are then ready to reproduce. They may clasp a nymph if no females have yet appeared, but as soon as a female appears a male will find her and clasp her, the venter of the female in close contact with the venter of the male. It is certain that. Fig. 1.—The chicken mite (Dermanyssus gallinae) : Fe- male mite before engorgement. Greatly enlarged. (Bishopp and Wood.). Please note that these images are extracted from scanned page images that
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