[Biology of lapwing lice].

(1) An analysis of the correlation between the number of chewing lice appearing on the nestlings of lapwing and their age is presented (fig. 2). As soon as a few hours after hatching most of the birds are parasitized by at least two species of mallophaga. Specimens of Quadraceps rapidly increase in the total during the first week of the host's life. At this time they predominantly inhabit the down on the belly. On waders this genus is abundant and generally takes the dominant position in frequency, while members of the superfamily Amblycera remain scarce components in the simple communities constituted by the parasites (fig. 3). -- (2) Nothing is known about a niche overlap of Austromenopon and Actornithophilus. Probably some competition exists between these genera on a certain host, as the mean-times of numerous occurrence and of transmigration from a parent bird to the nestlings are different in the two species considered (fig. 1). Confident generalization are not permitted, however. (3) Quadraceps junceus is an habitual blood-feeder. Most females of this species are haemophagous when invading the nestlings but males select blood only occasionally. The difference in food preference shown by the sexes proved to be highly significant and may be innate. Hence, perhaps the females have to seek a blood meal before maturation of the eggs just as mosquitoes do. Actornithophilus swarmed from the corpus of its host immediately fro considerable distance. (4) In sporadic cases overcrowding of feather-lice occurs even on birds which show no signs of weakness or injury. So far such outbursts of a population have been found only on full-grown birds, however. Here an example is given concerning a lapwing's nestlings that had hatched the same morning. In turn, attention is drawn to the factors normally regulating the variation in the order of dominance among the parasites involved and limiting their population-size. As a rule juvenile birds possess larger populations of mallophaga than adults do (fig. 4).