THE TERRAPIN SCALE. 



37 



Table XXV. — Rate per hour and distance traveled by a migrating larva of the terrapin 

 scale upon wrapping paper during the total time of the twigward migration, Mont 

 Alto, Pa., 1912. 



LARVA NO. 1. 





Observed— 



Interval . 



Distance. 



P t ate per 

 hour. 



Tempera- 

 ture. 







Min. 



Cm. 



Cm. 



° F. 



70 







30 

 15 

 30 

 30 

 15 

 15 

 15 

 45 



30.6 

 27.8 

 62 

 61.5 

 16.2 

 15.4 

 9.1 

 9.3 



61.2 

 111.2 

 124 

 123 

 64.8 

 61.6 

 36.4 

 12.4 



84 





3 30 p. m. 



88 







90 



Aug. 30< 



4.30 p. m. 



80 







78 





5 p. m 



77 







76 



• 



6 p. m , 



Total. 



72 





3h. 15 m. 



231.9 









2.30 p. m 















70 





3.15 p m 



45 

 15 

 45 

 15 

 90 

 30 



8 



1.7 

 17.3 

 3.2 

 8.6 

 2.7 



10.6 

 6.8 

 23.06 

 12.8 



5.7 

 5.4 



86 





3.30p.m... 



88 



Aug. 31 



4.15 p. m 



4.30 p. m 



82 



78 





6 p. m 



75 





6.30 p. m 



72 





Total 







4h. 



41.5 























70 





9.20 a. m 



35 

 10 

 30 

 60 

 60 



3.6 

 .4 



7.9 

 25.1 

 12.1 



6.17 

 2.4 

 15.8 

 25.1 



12.1 



72 



Sept. 1 



9.30 a. m 



80 



10 a. m 



86 





11 a. m 



88 







84 





Total...! 







3 h. 15 m. 



49.1 















Migration, first day: Migration started at 2.45 p. m., and continued until6p. m., when 

 it stopped. The larva remained motionless all night. During the time of migration, 

 which was 3| hours, the larva traveled 231.9 cm. It traveled at a rate of 124 cm. per 

 hour from 3.30 p. m. to 4 p. m., with a rate of 123 cm. per hour from 4 to 4.30 p. m. 

 The rate then fell off rapidly after 4.30, being 36.4 cm. per hour for the interval from 

 5 to 5.15 p. m., and only 12. 4 cm. per hour for the interval from 5.15 p. m. to 6 p. m. 

 The temperature during this migration rose gradually from 70° F. at 2.45 p. m. to 

 90° F. at 4 p. m. , and then fell to 72° F. at 6 p. m. The highest rate of travel therefore 

 coincided closely with the time of highest temperature. 



Migration, second day: The larva remained motionless from 6 p. m., August 30, until 

 2.30 p. m., August 31, when it again started to migrate and continued until 6.30 p. m., 

 an interval of 4 hours, during which it showed signs of exhaustion and traveled only 

 41.5 cm. The rate per hour gradually increased from the start until it reached a maxi- 

 mum of 23.06cm. per hour for the period 3.30 p. m. to 4.15 p. m., after which it dropped 

 to 12.8 cm. per hour during the next interval and then to 5.4 cm. per hour for the last 

 interval. The temperature during tMs second day's migration was slightly lower than 

 on the previous day. The temperature at the resumption of migration, 2.30 p. m., 

 was 70° F., from which it rose rapidly to a maximum of 88° F. at 3.30 p. m., and then 

 dropped gradually to 72° F. at 6.30 p. m. 



Migration, third day: The third day was very warm. The larva had remained 

 motionless from 6.30 p. m., August 31, to 8.45 a. m. of the following day, at which 

 time it resumed migration and continued until 12 noon, when it died, after traveling 

 for 3 \ hours, during which time it advanced 49.1 cm. The rate of travel, which was 

 very low, reached its maximum of 25.1 cm. per hour in the interval ending at 11 a. m., 

 after which it dropped to 12.1 cm. per hour for the interval between 11 a. m. and 12 

 noon. The temperature during the third day was very favorable. It reached 70° F. 



