28 



BULLETIN 416;, U. S, DEPARTMENT OF AGEICULTUEE. 



Manner of travel. — An extensive series of experiments concerning 

 the travel of red spiders has been performed. The female travels 

 in a comparatively straight course, being influenced by the light. 

 (PI. VI.) The female travels faster than the male and her effort is 

 extended over a relatively large space in an apparent attempt to 

 locate new food plants. The very frequent observance of sohtary 

 females on seedling plants is positive evidence that they estabUsh 

 themselves through the agency of ground travel. 



The male, on being removed from the host plant and tested on 

 a comparatively smooth surface, confines his wanderings to a small 

 area. The tracings made of male travel are seen to cross and recross 

 until a maze of lines results. No evidence of phototropism has been 

 observed in many cases of male travel. There seems to be an in- 

 stinctive tendency to remain within a hmited area. The entire area 

 traversed in an hour by the average male on a smooth surface rarely 

 exceeds in size that of a watch crystal. The aversion to roaming 

 probably originates from the instinctive desire to remain with the 

 females of the colony. It is not essential to the propagation of the 

 species that migrating females, which failed to mate before under- 

 taking their journeys, should become fertihzed immediately upon 

 estabhshing themselves on the new host. As has been emphasized 

 previously, the early eggs of such sterile females produce only males, 

 which, upon maturity, immediately fertihze the females, so that the 

 subsequent progeny will be of either sex. 



Table IV. 



-Distance and rate of travel of male and female red spiders on coarse paper 

 surface.^ 



Male. 



Female. 





Warm Day. 



Warm day. 



Cool day. 



Exp. No. 



Time. 



Dis- 

 tance. 



Rate 



per 



minute. 



Exp. 

 No. 



Time. 



Dis- 

 tance. 



Rate 



per 



minute. 



Exp. 

 No. 



Time. 



Dis- 

 tance. 



Rate 



per 



minute. 



1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



11 



12 



13 



14 



Mins. 

 30 

 30 

 30 

 30 

 12 

 8 

 15 

 15 

 40 

 16 

 15 

 15 

 45 

 30 



Ft. In. 



4 ^ 



5 9 

 5 6 

 5 2 

 2 1 



2 

 5 7 

 4 5 



12 7 



3 7f 



5 ^ 



4 8 

 9 3f 



7 3 



Inches. 

 1.68 

 2.30 

 2.20 

 2.06 

 2.08 

 3.00 

 4.47 

 3.53 

 3.78 

 2.73 

 4.30 

 3.73 

 2.48 

 2.90 



15 

 16 

 17 

 18 

 19 

 -20 

 21 

 22 

 23 

 24 

 25 

 26 



Mins. 

 31 

 26 

 60 

 60 

 30 

 60 

 30 

 30 

 21 

 31 

 26 

 30 



Ft. In. 

 10 11 



10 7 

 18 9 

 26 

 13 9 

 20 9i 

 13 14 



8 m 



11 11' 

 10 10 



10 7 

 13 8 



Inches. 

 4.25 

 4.85 

 3.75 

 5.20 

 5.50 

 4.16 

 5.25 

 3.55 

 6.80 

 4.20 

 4.90 

 5.47 



27 

 28 

 29 

 30 

 31 

 32 

 33 



Mins. 

 60 

 60 

 60 

 60 

 30 

 30 

 45 



Ft. /«. 

 9 



8 101 

 6 If 

 6 3 

 4 4 



3 m 



9 li 



Inches. 

 1.80 

 1.77 

 1.23 

 1.25 

 1.60 

 1.55 

 2.43 



Av.. 







2.95 









4.82 







1.66 





















' The mean temperature at the time of conducting the warm-day experiments was'91.2° F., and at the 

 time of conducting the cool-day experiments was 62.7° F. 



