92 • LOWER PTERYGOTA 



The life history is a matter of adaptation to different 

 ])lants. There are probably several generations in one 

 summer and liibernation in mature larval or adult stage. 



Mullein Thrips {Phloeothrlps verbasci). — ^The mullein thrips 

 has a definite restricted food plant and the herbivorous 

 character of the insect can be easily established. It is a little 

 l)lack species found in mullein ])lants the year through. 

 In early spring they are found among the bases of the mullein 

 leaves. They seldom try to fly, but creep about among the 

 fine hairs of the mullein leaf. They are very common in the 

 mullein plants and there are very few plants without them, 

 so examples may almost certainly be found wherever mullein 

 occurs. The eggs are laid soon after the leaves are Avell 

 started in the spring and there is a pretty definite brood. 



The adults of this brood mature about the time the blos- 

 soms appear, this being the softest portion of the plant 

 at this period. Later on adults in resting period are found 

 in seed pods or secreted around the base of the plants. 

 There are two generations in the summer fthe adult individ- 

 uals appearing first in the spring, then again in the sum- 

 mer, and again in the autumn. They do not do any great 

 damage to the leaves, although they feed upon this plant 

 exclusively. 



Another species, Phloeothrips nigra, occurs in clover 

 bloom. It is a black species and evidently restricted to 

 clover. The larva is bright red and often found during 

 the winter. They feed on part of the clover bloom and so 

 far as it has any eft'ect, is destructive to the clover. One 

 species is credited with feeding upon the grape Phylloxera. 

 If it does this it is an exception to the usual food habit of 

 the family. It possibly may feed ordinarily upon the tissue 

 of the gall and exceptionally on the plant lice that occur 

 within the gall. 



The group as a whole is to be considered as herbivorous 

 rather than carnivorous, and injurious when occurring on 

 useful plants. 



