1917] ECONOMIC ZOOLOGY — ENTOMOLOGY. 859 



resembles Rocky Mountain spotted fever, varies from 20 to 50 per cent. In 

 this paper tlie authors deal at length with the morphology and biology of the 

 mite, for which they suggest the generic name Leptotrorabidium. A bibliog- 

 raphy of 16 titles is included. 



Is Trombidium holosericeum the parent of Leptus autumnalis? M. Nagayo, 

 Y. MiYAGAWA, T. MiTAMURA, and A. Imamura {Jour. Expt. Med., 25 (1917), No. 

 2, pp. 273-276, pi. 1). — While the tsutsugamushi, Lcptotrombidiuin (Trom- 

 bidium) akamushi, is almost identical with the European L. autumnalis, the 

 authors' observations and study of the literature failed to convince them that 

 T. holosericeum is the parent of L. autumnalis. Regarding the host relations 

 of L. autum7ialis the authors state that " there is perhaps no mammal, which 

 comes within tlioir reach, unmolested by them ; they have been found on hares, 

 rabbits, various kinds of mice, badgers, hedgehogs, molebat, shrew, dogs, and 

 cats. On birds, reptiles, insects, and spiders I could, however, not effect any 

 infestation, though on insects and spiders near relations of L. autumnalis 

 parasitize. Our tsutsugamushi attacks field mice, rabbits, guinea pigs, mon- 

 keys, and other mammals, but not insects." 



Notes on parasitic acari, S. Hirst (Jour. Zool. Research, 1 (1916), No. 2, pp. 

 59-81, figs. IJf). — These notes relate to some species of acari parasitic on mam- 

 nials and birds in Great Britain and include descriptions of two new African 

 mites of the family Gamasidse. Keys are given to the species of the genera 

 Haemogamasus, Dermanyssus, and Laelaps occurring in Great Britain. 



The chicken mite: Its life history and habits, H. P. Wood (U. S. Dept. Agr. 

 Bui. 553 (1917), pp. 14, pl- 1, fios. 2). — This is a report of studies made at 

 Dallas, Tex., of tlie main points in the life history and bionomics of Der- 

 manyssus galUnce, especially those of importance in the application of control 

 measures. 



The incubation period of the eggs during the latter part of August at an 

 average mean temperature of 78.43° F. was about 48 hours. At an average 

 mean temperature of 73.5° the larva molts in about 24.5 hours without ever 

 having fed. At an average mean temperature of 82.9° the first stage nymphs 

 molt in somewhat less than 24 hours. With the exception of one individual 

 observed the second stage nymphs molted to adults in 3 days after feeding. 

 Fertilization normally takes place off the host and usually before feeding, fol- 

 lowed by oviposition within about 12 hours after feeding. Females deposit an 

 average of 4 eggs each at the rate of 4 eggs in 24 hours and they will continue 

 to feed and deposit at least eight times with one fertilization. 



The details presented relating to the life cycle show 10 days to have been 

 the actual time taken to pass through the life cycle under favorable conditions, 

 but under natural conditions it is thought that the period would be reduced 

 in August to at lea.st 8.5 days. A certain amount of moisture and a moderate 

 temperature were foiuid to favor longevity, while extreme dryness and high 

 temperatures are unfavorable factors. Under favorable conditions during July, 

 August, September, and October, adults and second stage nymphs lived from 91 

 to 98 days. The longest period for adults which had never fed was 88 to 96 days 

 during October, November, December, and January. The longevity of the 

 first stage nymphs was found to be about the same as the other stages. During 

 the months of September to January, inclusive, all stages on wood lived from 

 91 to 113 days, while stages in a glass chimney with a cracked egg lived more 

 than 107 days during the same months. The conclusions drawn from these 

 observations are that the mite can be starved out of a chicken house by keep- 

 ing fowls and other animals away from the house for four months during 

 the summer season and for 5 months during the cooler season in the latitude 

 of Dallas, Tex. 



