THYSANOPTERA AND ORTHOPTERA. 215 



4. The method of flight and leaping was found to be somewhat different 

 from that previous^ described. 



5. The method of copulation in those members of the suborder Tere- 

 brantia which were observed is different from that found among 

 the TubuHfera, in that the males are not carried by the females. 



6. Thrips of certain species are more abundant near highways than 

 elsewhere. This is probably due primarily to the fact that they 

 have been carried thither by traffic. Their failure to migrate from 

 the roads is not due to any preference for the roadsides, nor to in- 

 ability to fly far, nor to accident in attempted migrations; but is 

 apparently due to an internal factor. 



7. Of the checks to Thysanoptera, rains are probably most efficient. 

 The larva of one species was found susceptible to the effects of 

 water to the degree that it could endm'e complete immersion for 

 28 hours, but not for a much longer period. 



8. The distribution of thrips on their food-plants is not dependent on 

 the direction of ^ind or sunlight. 



9. A detailed record of the habitats from which each species was col- 

 lected has been preserved. 



Discussion of Economic Aspect. 



This phase of the subject has engaged the attention of entomologists 

 for years, and numerous papers have been issued from the experiment 

 stations. It ^nll therefore be but briefly discussed here. 



Owing to the fact that the regions studied were for the most part in 

 unsettled regions, I accumulated little data regarding the relation of 

 Thysanoptera to cultivated plants. In only one situation did I find 

 thrips doing any very noticeable damage to wild plants. This was the 

 work of Ctenothrips hridwelli on star-flowered Solomon's seal {Smilacina 

 stellata) and false lily-of-the-valley {Maianthemum canadense), on Sand 

 Point. These plants were found abundantly on but one small area, 

 and here was the only locality in which Ctenothrips hridwelli was taken. 

 It may prove that this species is comparatively highly specialized with 

 respect to its food. The leaves of the plants were nearly always con- 

 siderably blotched with white or yellowish, and many of them were 

 less than half green. At the time when the specimens were captured 

 here, they were not numerous, but must have been abundant earlier in 

 the season. 



On wild rye {Elymus canadensis) in one location, near a fisherman's 

 camp, I found as many as twenty-four adults and larvae of Anapho- 

 thrips striatals on a single young blade near the top of the stalk. Fung- 

 ous diseases, however, were so prevalent on these plants that their 

 weakened condition could not safely be attributed to thrips. 



