20 



BULLETIN 351, U. S. DEPARTMENT OF AGRICULTURE. 



the larvae by the fine soot deposit upon the smoked paper. The dis- 

 tance traveled varied from 97.7 cm. to 175.8 cm. Figure 6 shows a 

 tracing made by four of the above-mentioned larvae. 



Table XIII. — Record of travel of five first-instar terrapin-scale larvae on smoked paper, 

 Oct. 9, 1912, Mont Alto, Pa. 



No. 



Start. 



End. 



Time. 



Distance. 



Rate per 

 hour. 



Average 

 temper- 

 ature. 



1 



9.26a. m... 

 9.26 a. m . . 

 11.20 a. m. 

 10.08 a. m. 

 9.26a. m.. 



2p. m 



3.15 p. m.. 

 2p. m 



2p. m 



2.50 p. m.. 



Hrs. Min. 



4 34 



5 49 



2 40 



3 52 

 5 24 



Cm. 

 113.7 

 175.8 

 97.7 

 99.6 

 161.7 



Cm. 



26.54 



26. 596 



36.64 



25.76 



29.94 



° F. 

 87 



2 



86 



3 



89 



4 



87 



5 



86.7 













29. 095 



87 













The larvae are so small that they leave no trace when moving over 

 the finest soot deposit. The deposit, moreover, retards them. In 

 moving they are constantly exploring the surface with their antennae, 

 and these soon become coated with soot particles. When this hap- 

 pens the insect halts until the antennae are cleaned. (For compari- 

 son with the rate of progress upon smooth, unsmoked paper, see 

 Table XIV.) 



A single larva that emerged at 12.10 p. m traveled, when placed 

 upon plain wrapping paper, 826 cm. during the 3 hours and 20 min- 

 utes in which it was under observation. This larva traveled con- 

 stantly after the first interval, and its speed was about eight times 

 that of larvae on sooted paper, 

 this larva. 



Figure 7 shows a tracing made of 



Table XIV.— Record of the travel of a newly emerged larva of the terrapin scale on plain 

 'wrapping paper, July 10, 1912, Mont Alto, Pa. 



Time of observa- 

 tion. 



Tempera- 

 ture. 



Total dis- 

 tance. 



Interval 

 distance. 



Rate per 

 hour. 



Average 

 tempera- 

 ture. 



12.10 p. m 



12.25 p. m 



1 p. m 



o F 



86 



86 



86 



86 



86 



87.5 



87.5 



88 



Cm. 



Cm. 



Cm. 



° K 



35.3 



184.4 

 239.3 

 298.3 

 473.4 

 557.2 

 826 



35.3 

 149.1 



44.9 



59 

 175.1 



83.8 

 1S8 



141.2 



255.6 



179.6 



236 



262. 65 



251.4 



282 



86 



86 

 86 

 86 



86.75 

 87.75 



88 



1.15 p. m 



1.30 p. m 



2.10p. m 



2.30 p. m 



3.30 p. m 











231.356 



S6.9 











In 1912 three experiments were performed to determine the longev- 

 ity of the leafward migrants when they were unable to reach the 

 leaves. The data from these experiments are recorded in Table 

 XV, and summarized in Tables XVI and XVII. They show that 



