THE RED-BAN DEU TflKU'S. 



27 



opment beiore cliangiiijj; to pupa^, with iui avcrajzo moan tcmpera- 

 tiiro of about 71 ° F. (Scr Table III. ) 



Tahlk III. -lA'iif/tlio/pirjiiipalxfdjicn/'Ueliolkrip.siithniciiKliin In (/irnifioii;.'' at W-ixh- 



i)i(/l()ii, I). C, April, 191 >. 



1 Approximate. 



A number of i)iipse in the greenhouse required from four to seven 

 days for development, with an average mean temperature of from 

 68° to 70° F. 



Table IV. — Length of pupal stage of Ucliothrips rubrocinctus in greenhouse at Wash- 

 ington, D. C, April, 1912. 



Number 

 changed 

 to pupa. 



Date 



pupa 



changed 



to adult. 



(Apr. 16 » 

 tApr. 162 

 (Apr. 17 

 \Apr. 18 

 (Apr. 19 

 \Apr. 20 

 (Apr. 20 

 lApr. 20 

 Apr. 27 

 Apr. 24 

 /Apr. 21 

 \Apr. 22 



Number 

 changed 

 to adult. 



Minimum 



length of 



stage. 



Days. 



Maximum | Average 

 length of \ mean tem- 

 stage. perature. 



Days. 



o jp 



70.75 



68. 5 



69. 37 

 69.75 

 67.5 



I 9 a. m. 



» 1 p. m. 



In Trinidad tliis thrips ro(iuires 12 days from the time the egg 

 hatches until the adult appears, and with an estimated period of 

 4 to 6 days for the egg stage the life cycle will be approximately 16 

 to 18 days. Observations in a greenhouse at Washington, D.C., gave 

 a total life cycle of 28 days as a minunum to 43 days as a maximum, 

 with an average mean temperature of about 70° F. In Florida the 

 life cycle may require only 20 days as a minimum, but during parts 

 of the year at least will require in some cases 43 days for the com- 

 plete life cycle and possibly even longer. This insect will probably 

 have at least 10 generations annually in Florida. ^ 



