12 THE TOBACCO THRIPS. 



the inside and thus catching the young thrips, which readily succumb 

 Avhen so caught. 



Life cycle. — The life cycle of this species is found to be quite short 

 and very similar to that of the closely related wheat thrips, Evthrips 

 tritici. In May and June only twelve or thirteen days are required 

 for its completion. In the tobacco field the eggs appear to be depos- 

 ited in the tissues on the under surface of the leaf. In May and June 

 the incubation period for eggs laid in confinement in young bean 

 pods seems to average about four days. The larvse, upon hatching, 

 feed on the under surface of the leaf; during this stage, which lasts 

 seven days, and before changing to pupoe, they molt twice. When 

 al)out to pupate the larva^ crawl to some obscure nook; there they 

 remain inactive, without feeding, during the pupal stage, which lasts 

 two days. The adults, on emerging, have a yellowish color, which 

 in a few hours turns to the normal brown. As adults the thrips crawl 

 to the upper surface of the leaf and commence feeding. 



Hibernation. — The tobacco thrips appears to hibernate in the adult 

 stage. Wlien the fields were visited, the latter part of October, not a 

 specimen could be found, although another thrips {Ghirothri'ps 

 crassus Hinds), which was taken in large numbers in sheaths of 

 grass found growing in the tobacco fields, was at first mistaken for 

 the tobacco thrips. Mr. W. W. Cobey informed the writer that he 

 had observed the tobacco thrips on the leaves of cocklebur about 

 October 10, previous to a cold spell. Thus it would seem that the 

 thrips goes into hibernation after the first approach of cold weather. 



OTHER THRIPS THAT MAY BE MISTAKEN FOR THE TOBACCO 



THRIPS. 



While the tobacco thrips is the only species commonly found on 

 tobacco, yet a number of other thrips which may be mistaken for this 

 pest are found in the vicinity of the tobacco fields, or even acci- 

 dentally upon the tobacco itself. Among those that may be so mis- 

 taken are the following species : 



Euthrips tritici Fitch, the " wheat thrips," is a species generally 

 distributed throughout the South. It has a wide range of food plants 

 and can be found during a large part of the year in almost any blos- 

 som. In Florida it has been reported as injuring the orange and 

 strawberry by attacking the blossoms. At Quincy, Fla., during the 

 summer of 1905, it was found in large numbers associated with the 

 tobacco thrips in oat fields bordering the tobacco fields. It was also 

 found seriously injuring roses, causing the outer petals to wither 

 before the flowers opened. It may be distinguished from the tobacco 

 thrips by the yellowish color of the adult or winged form, which in 

 the tobacco thrips is dark brown. 



ThripH tahaci Lind., the " onion thrips," has been reported by Prof. 

 A. L. Quaintance as quite abundant in Florida, attacking onions. 



