108 



DISEASES OF CROPS. 



Prevention. — Infested seeds should not be sown. 

 Farmers should make a practice of examining their seeds 

 — and especially foreign seeds — before sowing or drilling. 



Cure. — (1) " Kiln-drying, if judiciously performed, 

 would destroy the larvse, without affecting the germinat- 

 ing power of the seeds. About 120° F. is held by some 

 authorities to be a safe and sufficient maximum of heat 

 to accomplish this." But it must be borne in mind that 

 kiln-drying is of use only for comparatively new seed. 



Pig. 42. — CoEN Thrips {Thrips cerealium). 



A. Corn thrip (enlarged). 



B, Its nat. size. 



0. Larva of thrips (enlarged). 



What would be the use of kiln-drying seeds which have 

 already lost the greater part of the farinaceous matter 

 and possibly the germs damaged by the larvse of this 

 pest ? It is impossible for such seeds to produce any- 

 thing like satisfactory crops. (2) Washing the floors, 

 etc., of granaries with soft soap and paraffin oil, and lime- 

 washing the ceilings, destroy this pest. 



The Wheat or Corn Thrips {Thrips cerealium, 

 Thrips tritici, Fig. 42)i belong to the natural order 

 Physopoda. The members of this order are generally 



1 For an excellent account of various species of Thrips, see Linde- 

 man's Die am Getreide Lebenden Thrips arten Mittelrusslands, pp. 

 1-42. 



