BEHAVIOR OF SPIDERS AND OTHER INSECTS 395 



throughout the larval period, after metamorphosis, and even for 

 a short time after mating. Soon after ovipositing, the female 

 becomes gradually indifferent and then positively phototactic. 

 He has also disproved the common belief that, immediately 

 after metamorphosis, the carpet beetle goes outside of the house 

 to breed. He found that the carpet beetles popularly known as 

 " buffalo moths " (Anthrenus scrophulariae) and the black carpet 

 beetles (Attagenus piceus) respond to light in the same manner 

 as Trogoderma tarsale. 



By means of field observations (117), Weiss discovered that 

 different species of mosquitoes are quite unlike in their behavior 

 towards light. Some are equally positively and negatively 

 phototropic, some are unequally positively and negatively pho- 

 totropic and others are constantly one thing or the other. Up 

 to a certain low intensity of light, Culex pipiens, C. aurifer, 

 C. canadensis, C. sylvetris, C. sallinarius, Anpheles maculipennis 

 and Wyeomyia smithii are positively phototropic; beyond that 

 they are negatively so, and normally appear only at night. Near 

 the close of the season, impregnated females of C. pipiens become 

 strongly negatively phototropic and seek dark hibernating 

 quarters. A. crucians is positively phototropic up to noon-day 

 intensity of light. A. punctipennis responds both negatively 

 and positively, but more often negatively. C. perturbans is 

 negative in its reactions. At one place, Weiss asserts that C. 

 sollicitans appears to be equally negatively and positively pho- 

 totropic and that the reaction is evidently dependent upon 

 nutrition. This does not harmonize with his statement that C. 

 sollicitans, C. cantator and (7. taeniorhynchus , all salt-marsh 

 forms, are positively phototropic; but that C. salinarius, also a 

 salt-marsh form, is negatively phototropic. 



Holmes and McGraw (60) have devised an excellent method 

 of studying the light responses of insects. A cylindrical jar, 

 the bottom and side of which are covered with white paper, is 

 covered with- a cone of the same material, the apex of which 

 conceals an electric light. A small peep hole permits the in- 

 vestigator to view the interior of the vessel. A circular dish 

 containing the subject of the experiment is placed on the center 

 of the floor of the jar. No matter which way the insect turns, 

 the illumination is of the same intensity. Insects with one eye 

 rendered opaque were placed in the jar and stimulated to action. 



