1918] 



Marchand — A Thermotropism in Anopheles punctipennis 



133 



by J. B. Smith (Mosquito-control exhibit, N. J. State Museum),^ 

 in which it is represented to form a right angle with the surface, is 

 an extreme case and not quite typical. It seems, 

 however, that mosquitoes which rest for many 

 hours in the same place, assume a more oblique 

 position than do these which have just alighted. 

 These characteristics apply only to Anopheles 

 punctipennis, not to A. quadrimaculatus . Hiber- 

 nating females of the latter species were ob- 

 served beyond doubt in a resting position in 

 which the body was held about parallel to the 

 resting surface, as illustrated in the accompany- 

 ing drawing from nature (Fig. 1). Hence, they 

 can be easily mistaken for Culex if only the resting 

 position is taken as a criterion .- 



Concerning the biting position of Anopheles, 

 Nuttall and Shipley's illustration (J. B. Smith, 

 N. J. State Museum exhibit) is not entirely 

 correct (Washburn) ,3 and H. P. Johnson* is in error in 

 assuming that the mosquito must necessarily bite with proboscis 

 inserted at a right angle. As a matter of fact, A. punctipennis 

 will insert the proboscis usually at an oblique angle, the mosquito 

 biting in a position much like the resting position, and the line of 

 the proboscis forming the continuation of the longitudinal axis of 

 the body. This is evidently of advantage for the sucking mech- 



Fig. 1. Resting 

 position of hiber- 

 nating female of 

 Anopheles quadri- 

 maculatus. 



Sketch-drawing 

 from Life. 



anism. 



III. The Biting Instinct due to a Thermotropic Recu;tion. 



Observations were also made on the biting instinct, which as it 

 seems, is determined mainly by thermotropism. Patton and 

 Cragg (1913) have reported^ that Howlett observed that females of 



» Nuttall and Shipley. The structure and biology of Anophdes maculipennis, Jour, of 

 Hygiene, 1901. 



' Howard (loc. cit. p. 205) has recorded the same fact for A. quadrimiculstus hibernating in 

 barns in southern Idaho. 



» Washburn, F. L. Economic Entomology at the World's Fair. Science N. S., Vol. 

 XX, No. 518, 1904, and "The Biting position of Ano.-heles." Science, N. S., Vol. XXI, p. 

 228, 1905. 



« J. B. Smith. How does Anopheles bite? Science, N. S., Vol. XXI, pp. 71-72, 1905. 



'Patton and Cragg. Textbook of Medical Entomology. London, Madras and Calcutta, 

 1913. 



