GRASSHOPPERS AND OTHER INJURIOUS INSECTS OF 1911 AND 1912. 25 



tions in the field, which were later confirmed by extended laboratory tests, 

 convinced us that a very high percentage of the young "hoppers" which clus- 

 ter upon this cloth wing become covered with kerosene and die within a short 

 time although they may hop from the wing and apparently escape. The fol- 

 lowing is taken from Mr. Stoner's notes at the conclusion of a long series of ex- 

 periments and observations testing the effect of kerosene in small quantities 

 applied to the bodies of young grasshoppers and the effect of throwing the 

 "hoppers" lightly against a cloth screen wet with kerosene: "These experi- 

 ments would seem to substantitate the statement that "even if a hopper merely 

 hits the canvas back of the hopperdozer, this canvas being well saturated with 

 kerosene, the hopper will be killed." 



In use the pan is filled about half full of water to which is added from 

 one to two quarts of kerosene. The "wing" is then drenched with kerosene 

 and the hopperdozer is dragged through the fields. Grasshoppers rising be- 

 fore this "clozer" strike against the "wing" or fall into the pan, in either case 

 becoming wet with the kei'osene which kills them in a very few minutes. The 

 time of action with the hopperdozer, as with all other methods of control is 

 very important. The best results can only be obtained if the "dozers" are used 

 early in the season, that is, from the middle of May to the middle of June. At 

 that time the young grasshoppers, not having developed wings, cannot fiy over 

 the wings and escape as many of them are sure to do when the use of the ap- 

 paratus is delayed until late in summer. The cost of the "dozers" made as 

 above, is very low. During the past summer they have been made throughout 



Fig. 17. A convenient grasshoijper collecting box, used in field. C. W. Howard. 



the Red River Valley at prices ranging from five dollars to eight or nine for the 

 sixteen foot size. It is not necessary to use kerosene of a high grade, in fact 

 in this case the cheapest is the best and grades of oil ranging from seven to 

 ten cents per gallon (at the supply tanks) were found perfectly satisfactory. 



As has been said, this device should be used early, practically the only 

 test of time being that the grasshoppers must be able to jump high enough to 

 fall into the pan and this they are able to do within a surprisingly short time 

 after their first appearance. 



In cases where fields adjoin large tracts of unused lands which are badly 

 infested with grasshoppers, we found it possible to restrain these young hop- 

 pers within the unused land by plowing a strip two or three rods wide between 

 the edge of the infested area and the cultivated area. This is of course merely 

 temporary relief but in cases when the young hoppers are beginning to swarm 

 out of such areas and into the young grain, while still too small to permit of 

 the effective use of the "dozer". Young hoppers traveling as they do only by 

 hopping, pass over such barriers only with the greatest difficulty, and in fact 

 very few passed over such plowed strips when used early in the season. It is 

 evident that the supply of hopjjers within the infested area is in no way di- 

 minished by this and that unless some means of exterminating them there be 

 applied they will presently pour out upon the fields in full force. 



The plow has been said to be one of the most efficient tools to use against 

 grasshoppers and while there is much truth in the statement, yet like many 



