June, '11] 



quayle: scale ixsect locomotion 



Red Scale {ChrjsoTn-pha'iu-s aurantii Mask.) 



303 



Purple Scale (Lepidosaphes beckii Newm.) 



traveled in the two-hour period was 111 inches. In most cases these 

 experiments started off with four insects but some would be lost or 

 destroyed, so that completed records are given for but one in some 

 instances. But since it was more desirable to have the maximum 

 rate of travel in each case, one record, in the case of the higher tem- 

 peratures, answers the purpose. With the purple scale the maximum 

 distance traveled was 37.95 inches when the temperature was 68° 

 and a total of 111 or more than three times the distance when the 

 temperature was 89°. 



Taking the maximum Hfe of the active larva of each of these scales 

 at 4 days, which seems from our experiments to be about correct, 

 the possible maximum distance traveled during the period may be 

 calculated. For the black scale the maximum rate of crawling for a 

 two-hour period is 15 feet. If it continued at this rate without stop- 

 ping for 4 days it would travel a total of 720 feet, but this is never 

 actually done under natural conditions. In the first place it would 

 never have as smooth a surface as paper to crawl over, and again 

 it is not at all likely that such a rate of speed would be maintained 

 constantly. On the same basis of calculation the red and purple 

 scales would each travel a maximum distance during their active 

 period of 444 feet. These scales almost invariably settle within one 

 or two days after emerging, but in the absence of food they might 

 continue to be active for 4 days. The purple and red scales travel 

 at about the same rate for both the minimum and maximum tempera- 



