146 



As regards domestic animals the data for 1917 show that horses, 

 cattle and pigs are efficient as tick hosts in the order named, and 

 that pigs running at large will pick up large numbers of ticks. 



The factors that determine the species of host-animals and their 

 relative abundance are the character of the ground, whether rocky 

 or clear, and the nature of the vegetation. For example, in prairie 

 country, only prairie animals can become sufficiently numerous to 

 become a real factor in tick abundance. It has been found that certain 

 animals, which under prairie conditions are found both in rocky 

 and rock free areas, always yield more ticks when taken in the rocky 

 situations. 



CocKERELL (T.D. A.). The Mosquitoes of Colorado. — Jl. Econ. Entom., 

 Concord, N H., xi, no. 2, April 1918, pp. 195-200. 



The necessity of establishing a number of military recuperation 

 camps in the most favourable localities led the author to begin a 

 mosquito survey of Colorado, as, according to the data in the mono- 

 graph of Howard, Dyar and Knab, the only area in the United States 

 free from Anopheles consists of eastern Colorado, Wyoming, Nebraska 

 and the Dakotas. It is not probable that Anophelines are actually 

 absent from the whole of this area, but even if locally present, they can 

 often be readily exterminated owing to the limited possible breeding 

 places. 



The species so far definitely identified from Colorado or Wyoming 

 are the following : — Anopheles qnadfimacnlatus, Say, recorded only 

 from the far western part of the State ; Cnlex tarsalis, Coq. ; C. pipiens, 

 L. ; Theobaldia inornata, Willist. ; T. incidens, Thoms. ; Aedes 

 acrophilus, Dyar ; A. aldrichi, D. & K. ; A. cinereus, Mg. ; A. curriei, 

 Coq. ; A. idahoensis, Theo. ; A. mimesis, Dyar ; A. nigromaculis, 

 Ludl. ; A. pullatus, Coq. ; A. sansoni, D. & K. ; A. stimtdans, Walk. ; 

 A. triseriat'us, Say, var. hendersoni, n. ; and A. vexans, Mg. 



EwiNG (H. E.) & Hartzell (A.). The Chigger-mites affecting Man 

 and Domestic Animals. — Jl. Econ. Entom., Concord, N.H., xi, 

 no. 2, April 1918, pp. 256-264, 1 fig. 



Chigger-mites, which are the larvae of the brightly coloured harvest 

 mites, though pests of economic importance have hitherto escaped 

 thorough investigation on account of their minute size. 



The species here dealt with are : — Metathronibidium poriceps, Oud., 

 the summer chigger of Europe, a very small, egg-shaped mite, not 

 more than '4 mm. when unengorged. It has been frequently reported 

 from man, and has been taken from the dog, and from chickens. 

 Among the invertebrate hosts are Mnsca domestica (house-fly) 

 and other insects belonging to many orders. It has also been recorded 

 from spiders, rodents and various mammals. It has been collected 

 in June, July, August and September, and is found in the Netherlands, 

 France and Germany, and doubtless occurs in other parts of Europe. 



Microthrombidium pusillum, Herm. (European harvest mite) was 

 long known under the name of Lepttis autumnalis and gives rise to 

 a severe rash or itch. Unengorged, these mites are brick-red in 

 colour, but so minute as to be scarcely visible to the naked eye. For 



