16 



BULLETIN 1225, U. S. DEPARTMENT OF AGRICULTURE. 



Table 3. — Length of life of adults of the camphor thrips, showing length of egg-laying, 

 preoviposition, and postoviposition periods, together with number of eggs laid — Con. 



IN WINTER. 



Record No. 



Date 



adult 



emerged. 



Date 



first egg 



laid. 



Length 

 of pre- 

 oviposi- 

 tion 

 period. 



Date 



last egg 



laid. 



Length 

 of egg- 

 laying 

 period. 



Date of 

 death. 



Length 

 of post- 

 oviposi- 

 tion 

 period. 



Total 

 length 

 of life. 



Total 

 num- 

 ber of 

 eggs 

 laid. 



1 



1920-21. 

 Dec. 1 . . . 

 Nov. 8... 

 Nov. 12.. 

 Nov. 17.. 

 Dec. 28.. 

 Dec. 30.. 

 Jan. 2. . . 

 Jan. 7. . . 

 ...do 



1920-21. 

 Dec. 8... 

 Nov. 14.. 

 Nov. 17.. 

 Nov. 22.. 

 Jan. 7. . . 



Jan. 6 



Jan. 9. .. 

 Jan. 13.. 

 Jan. 15. . 

 Jan. 22. . 



Feb. 8... 

 Feb. 18.. 

 Feb. 8... 

 Feb. 25.. 

 Feb. 11.. 

 Feb. 14.. 

 do.... 

 Feb. 11.. 

 Feb. 16.. 



Days. 

 7 

 6 

 5 

 5 



10 

 7 

 7 

 6 

 8 



10 

 8 



10 

 9 

 7 



11 

 5 

 8 

 6 

 5 

 8 



1921. 

 Mar. 12.. 

 Mar. 18.. 

 Apr. 3... 

 Feb. 7... 

 Mar. 26.. 

 Apr. 26. . 

 Mar. 19.. 

 Apr. 7... 

 Jan. 25. . 

 Apr. 3... 

 May 10.. 

 Mar. 20.. 

 Apr. 29. . 

 Mar. 26.. 

 Apr. 9... 

 June 4... 

 Mar. 19.. 

 Apr. 24.. 

 Mar. 20.. 

 Apr. 11.. 



Days. 

 94 



124 



137 

 77 

 78 



110 

 69 

 84 

 10 

 71 

 96 

 40 

 70 

 47 

 43 



113 

 33 

 69 

 47 

 54 



1921. 

 Mar. 14.. 

 Mar. 19.. 

 Apr. 4... 

 Feb. 8... 

 Mar. 28.. 

 Apr. 28. . 

 Mar. 21.. 

 Apr. 9... 

 Feb. 4... 

 Apr. 5... 

 May 11.. 

 Mar. 21.. 

 May 1... 

 Mar. 28.. 

 Apr. 9... 

 June 6... 

 Mar. 20.. 

 Apr. 25. . 

 Apr. 3... 

 Apr. 16.. 



Days. 

 2 

 1 

 1 

 1 

 2 

 2 

 2 

 2 



10 

 2 

 1 

 1 

 2 

 2 

 

 2 

 1 

 1 



14 

 5 



Days. 



103 



131 



143 



82 



90 



119 



78 



92 



28 



83 



105 



51 



81 



56 



54 



120 



42 



76 



56 



67 



Eggs. 

 365 



2 



489 



3 



348 



4 



211 



5 



219 



6 



553 



7 



117 



8 



405 



9 



25 



10 



Jan. 12. . 

 Jan. 26. . 

 Jan. 29.. 

 Feb. 9... 

 Feb.l... 

 Feb. 14.. 

 Feb. 6... 

 ..do. . 



320 



11 



401 



12 



144 



13 



251 



14 



253 



15 



341 



16 



553 



17 



154 



18 



Feb. 8 

 Feb.6... 

 Feb. 8... 



404 



19 



260 



20 



327 









7.4 



73.3 



2.7 



82.85 



307 



1 I 









PARTHENOGENESIS. 



Reproduction of the camphor thrips seems to be almost entirely 

 by parthenogenesis. No males have ever appeared in the breeding 

 jars at any time of the year. Occurring in nature rather rarely, it 

 is doubtful if the males fulfill any necessary role in the propagation 

 of the species. Large numbers of the adults captured from trees 

 and placed together in jars have never shown any tendency toward 

 mating. The fact that isolated females have been reared for many 

 successive generations proves that they can reproduce throughout 

 the year parthenogenetically. The male larvae, which are rather con- 

 spicuous because of their purple coloring, were found most abundant 

 in January on the trees in the laboratory yard. Some occurred 

 throughout the spring and until June, but none were seen during 

 the summer. These larvae when raised to adults in jars and placed 

 together with recently matured females were never seen to mate. 

 Neither did these females produce any offspring which showed any 

 purple color like the immature males. In fact a purple larva never 

 was produced in any of the life-history work. 



FLYING HABITS. 



Although provided with fully developed wings, the thrips seldom 

 fly, and flight is a small factor in the distribution of the species. 

 The maximum flight which has been observed was only a few feet. 

 Watson {2) also states that the thrips seem to be incapable of flight. 

 On a few occasions adult thrips were seen to fly from one limb to 

 another, but it is very doubtful if they ever attempt any long flight, 

 such as from one field of camphors to another, and seldom even from 

 one tree to another. In the breeding jars the adults often fly from 

 the camphor limb to the sides of the jar, and on one occasion a 



