418 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



moderately gregarious. They will sometimes cat newly sown 

 parsnip after the older plants originally attacked have been 

 destroyed, in such cases eating the tender green leaves, while of the 

 older plants they eat only the flower-heads and interior lining of 

 the stems." The moths appear in late July and early August. 



Control. Thorough spraying or dusting with arsenicals will 

 destroy the caterpillars, according to Chittenden. If the flowers 

 are destroyed before they are noticed, cut off and burn all infested 

 stems before the moths emerge from the pupa?. Obviously it will 

 be important to avoid planting parsnips in or near waste places 

 which have grown up in wild carrot. 



The Onion Thrips * 



The small yellowish " thrips " which chafe the epidermis from 

 the green leaves, causing them to dry out, whiten and die, have 

 become well known to onion growers in practically all parts of the 

 United States where onions are raised extensively. It is a Euro- 

 pean insect, occurring in Germany and Russia, and has also been 

 imported into the Bermudas. 



The adult thrips is about one-twenty-fifth of an inch long, of a 

 pale yellow color, tinged with blackish. The general appearance, 

 much enlarged, is shown in Fig. 302. The slender, elongate body 

 bears two pairs of narrow, bristle-like wings which are of no value 

 for flight. The fore-wing contains two wing- veins, and the hind- 

 wing but one, the posterior margin of both bearing a fringe of long 

 hairs. When at rest the wings lie together along the back. 



The thrips belong to a quite distinct order of insects, the 

 Thysanoptera (or Physapodd), species of which are commonly 

 found in the flowers of the rose and clover. The mouth -parts are 

 quite different from those of any other order of insects, being 

 intermediate between those of biting and sucking insects, the 



* Thrips tabaci Lind. Order Thysanoptera. See Quaintance, A. L., 

 Bulletin 46, Fla. Agr. Exp. Sta., " The Strawberry Thrips and the Onion 

 Thrips." Full account and Bibliography; Pergande, Th., " Insect Life," 

 Vol. VII, pp. 292-295; Osborne-Mally, Bulletin 27, Iowa Agr. Exp. Sta., 

 pp. 137-142; Sirrine, Bulletin 83, N. Y. Agr. Exp. Sta., pp. 680-683. 



