COAL-TAK AS AN INSECTICIDE. 51 



ncously in twenty-uino counties of the State. ***** j,^ ^^\^q 

 prosecution of this enterprise there were employed about 50,000 

 pounds of sheet-iron and 3,000 barrels of coal-tar, which required a 

 total expenditure of about $10,350." 



Another trap was employed in Colorado for destroying the locusts, 

 which is described as " a i)iece of oil-cloth, nine to twelve feet long 

 and six wide, one side and each end of which arc secured to light, 

 wooden strips by common carpet-tacks, the corners being strengthened 

 by braces. The oil-cloth being smeared with coal-tar, the trap is 

 dragged over the ground by two men, a cord about ten feet long being 

 fastened to the front corners for that purpose. The entire expense of 

 the trap is about $3.50." 



A still more simple trap has been used with very satisfactory success, 

 by substituting sheets of building paper for the oil-cloth, and coating 

 it with the tar. 



For more detailed accounts of these and other coal-tar traps, refer- 

 ence may be had to the Firsi Rejjort of the U. S. E)itomoIogical Com- 

 mission, 1878, pp. 387-391. 



It is evident that these traps may also be employed for the collection 

 of other low-feeding insects occurring in extensive numbers, especially 

 for the hopping species. 



A method of using coal-tar in the irrigating ditches in Colorado 

 may suggest somewhat similar methods for its use elsewhere. "It con- 

 sists essentially in pouring, or better, iu dropping coal-tar on the run- 

 ning water with which the irrigating ditches were supplied. It is only 

 necessary to sprinkle a few drops on the stream, when the oils con- 

 tained in the tar are diffused over the surface of the water, and coming 

 in contact with the insects (no matter how many), cause their speedy 

 death. The toxic power of coal-tar upon the insects is very remark- 

 able ; a single drop of it floating on the water is capable of causing the 

 death of a large number of insects." {First Rep, U.S.E. C, p. 382.) 



A convenient method of using coal-tar for the destruction of many 

 of the smaller insects that infest our garden, is to procure a coal-tar 

 barrel with a few gallons of tar remaining in it; fill with water and 

 use from it as needed with a sprinkler. It may ,be refilled a number 

 of times if the tar be occasionally stirred with a stick to disengage the 

 oil. Used in this manner, it is also a valuable deterrent from insect 

 attack. 



It has been stated (Coww/ry Gentleman, xli, 187G, p. 202), that a 

 gallon of coal-tar mixed with a pound of sulphur, placed in a frying- 

 pan and set on fire, and passed under plum-trees in the morning while 

 wet with dew, every other morning during the curculio season, made 



