1918] Marchand—A Thermotropism in Anopheles punctipennis 133 
by J. B. Smith (Mosquito-control exhibit, N. J. State Museum),' 
in which it is mepreseatet 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- 
er _ ing drawing from nature (Fig. 1). Hence, they 
Fig. 1. Resting c : : . 
position of hiber. Ccalbe easily mistaken for Culex if only the resting 
a ae es position is taken as a criterion.” 
at a Concerning the biting position of Anopheles, 
eae NE Nuttall and Shipley’s illustration (J. B. Smith, 
N. J. State Museum exhibit) is not entirely 
correct (Washburn),? 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- 
anism. 
III. The Biting Instinct due to a Thermotropic Reaction. 
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 
1 Nuttall and Shipley. The structure and biology of Anopheles maculipennis, Jour. of 
Hygiene, 1901. 
2 Howard (loc. cit. p. 205) has recorded the same fact for A. quadrimaculatus hibernating in 
barns in southern Idaho. 
3 Washburn, F. L. Economic Entomology at the World’s Fair. Science N. S., Vol. 
XX, No. 518, 1904, and “‘The Biting position of Anovheles.’’ Science, N. S., Vol. XXI, p. 
228, 1905. 
‘J.B.Smith. How does Anopheles bite? Science, N.S., Vol. XXI, pp. 71-72, 1905. 
5 Patton and Cragg. Textbook of Medical Entomology. London, Madras and Calcutta, 
1913. 
