246 Forty-ninth Report on the State Museum 



The eggs are elliptical, reddish, not more than 0.25 mm. long, and are 

 glued singly along the nerves on the underside of the leaves. At the 

 end of the summer they were found on the upper side also.* The egg 

 stage was found to last ten days. 



The larvae were observed to hatch in large numbers on the loth of 

 July. They remained on the leaves where they were first seen feeding 

 and growing until August loth, at which time they suddenly disappeared. 

 They were then found on the stalk and upper side of the leaves as nymphs. 

 A few scattering larvae were seen after August loth. Thus the larval 

 period is about 30 days. Of other species studied by Dr. Lindeman, 

 viz., Thiips secalina Lindmn., and Phhwthrips frumetitaria Bel., their 

 larval periods were found to be 28 to 30 and 35 to 40 days respectively. 

 The nymph stage was apparently from five to seven days. On the 27th 

 of August newly hatched larvae in large numbers again appeared — the 

 life-cycle of which was completed in 47 days. " The imago appears to 

 live but one day." 



Number of Generations. 



The first generation observed on the tobacco by Dr. Lindeman emerged 

 from eggs laid the last of June, matured, and oviposited about August 

 17th. From their eggs numerous larvas hatched on the 27th of the month 

 and matured about 37 days later, — imagoes appearing early in October. 

 The insect hibernates in the adult form, and flies the middle of the follow- 

 ing May. Thus there are three generations in a year in Bessarabia — 

 the first flying the middle of May, the second the last of June, and the 

 third the last half of August. The spring brood was not observed per- 

 sonally by Dr. Lindeman, but he was assured by many tobacco growers 

 that the seed beds were commonly infested by large numbers of Thrips 

 early in May. 



"The winter is passed in the larval or adult form, very hkely in each; 

 both stages being represented during the winter months and the adults 

 beginning the deposition of eggs as early in the season as the vegetation is 

 ready for them" (Osborn-Mally, /(S'r. citi). The above appears to be 

 the only record of how the insect passes the winter in this country. 



* According to Gsborn-Mally, loc. cit., p. 140: "The eggs are deposited slightly beneath the 

 surface of the leaf and imbedded in the cell-structure." There is a discrepancy between this and 

 Dr. Lindeman's observations. It certainly appears that the saw (PI. XV, fig. 3) of the female is 

 well adapted to making punctures for the reception of the eggs. The differences in habit noted 

 may possibly be due to the food-plant, Dr. Lindeman having studied the insect on the tobacco,, 

 and Gsborn-Mally on the onion. 



