No. 567] BIOLOGY OF THE THYSANOPTERA 171 



away from tlie window, they became wedged lightly be- 

 tween glass and blotter, and came to rest, the blotter with 

 all on it was turned through 180 degrees. The larvae 

 turned their bodies so that their heads were directed away 

 from the window, but did not crawl away. The positive 

 reaction to contact overcame the negative response to 

 light. 



An adult tested in the same manner as the larvae above 

 described did not come to rest under the glass square. 

 But happening to crawl against the microscope slide 

 which supported the glass, the thrips came to rest in the 

 right angle formed by the blotter and the edge of the 

 slide, and remained there a long time. 



Gravity. Exps. 13 and 20.— Adults and larvae were 

 put, one at a time, into a glass tube, which was set in a 

 vertical position, and covered with a black sleeve to ex- 

 clude light. Some were examined at frequent intervals, 

 others were left half an hour without examination. In 

 every case the thrips were found almost precisely where 

 they were put at the beginning of the experiment. This 

 species is therefore indifferent to gravity. 



Anthothrips niger 

 Light. Exp. 2. — The red larvaa of this species were 

 shaken out on a paper near a window, as described in 

 other experiments. In every case the larva crawled away 

 from the window for a few seconds at first, then slowly 

 turned toward the window, and continued indefinitely 

 toward the light. Once while the larva was crawling 

 toward the light, I tapped the paper vigorously with a 

 pencil, so that the thrips was lifted slightly from the 

 paper and let drop; it immediately reversed its direction, 

 crawling from the window, but in a few seconds turned 

 again toward the light. The paper was jarred frequently, 

 but always with the same result. To show whether the 

 jarring made the response to light negative, or merely 

 reversed whatever the larva was doing at the instant, the 

 tapping was repeated at intervals of one or two seconds. 



