April, '15] 



XEWELL: SUDAN GRASS INSECTS 



233 



One of our correspondents, Mr. A. S. Whitten, of Porterville, Texas, 

 has observed these insects hibernating in piles of wood, weeds and 

 trash generally. The method of hibernation would suggest, as reme- 

 dial measures, the early deep ploT\dng of infested fields and a thorough 

 winter cleaning up and burning of all rubbish affording hibernating 

 quarters for the insect. MorrilP also recommends the destruction of 

 all mesquite trees in the- vicinity of infested fields, as the mesquite is 

 one of the favorite native host plants of the insect. 



The Angoumois Geain Moth 



The Angoumois grain moth, Sitotroga cerealella Oliv., readily infests 

 the seed of Sudan grass both in the field and in storage. During 

 September and October, 1914, the moths were noted in great abun- 

 dance among the heads of the uncut grass at Robstown, Texas, as well 

 as in the shocks of harvested grain awaiting threshing. During the 

 w^armer days of November, also, they were abundant around the bins 

 in which the seed had been stored. 



Fortunately, Sudan grass seed shows a high resistance to injury by 

 carbon bisulphide. In experiments which we have made to determine 

 whether its germinating power might be affected by heavy fumigation 

 it was found that as much as 15 lbs. to the 1000 cubic feet of bisulphide, 

 confined for 12 hours, did not affect germination. In some instances 

 the fumigation even appeared to stimulate germination of the seed. 

 The germination tests were made in seed testers, both immediately 

 after the fumigation and again nine weeks later. The results of a few 

 of these fumigations are given in the table below: 



Germination op Sudan Grass Seed Fumigated with Carbon Bisulphide at Different Strengths 



Date of Fumigation 



Amount of CS.> 

 per 1000 Cubic Feet 



Per Cent of Germination, 

 Sept. 5-10 



Per Cent of Germination , 

 Nov. 16-20 



Sept. 1-0 



lib. 



91 



90 



Sept. 1-0 



3 lbs. 



88 



90 



Sept. 1-0 



5 lbs. 



97 



91 



Sept. 1-0 



8 lbs. 



83 



94 



Sept. 1-0 



10 lbs. 



91 



91 



Sept. 1-0 



15 lbs. 



86 



78 



(Not fumigated) 



Check No. 1 



86 



83 



(Not fumigated) 



Check No. 2 



88 83 



^ Bui. 89, Bureau of Entomology. 



