30 INSECTS OF ECONOMIC IMPORTANCE 



rial used in their tanglefoot fly paper. It is useful 

 in putting about the trunks of trees to catch canker- 

 worm moths, caterpillars of the tussock moth, etc. 

 Treeleim — A substance manufactured by the 

 Vreeland Chemical Co., which is used for the same 

 purpose as tanglefoot and is said not to ''glass" over 

 but to remain fresh and sticky a long time. 



SPRAYING 



History of spraying — The current worm be- 

 came injurious about i860 and the Col. Pot. beetle 

 about 1865. Hellebore and par is green were used 

 for these two pests, and this suggested the use of 

 the latter for other insects. Riley suggested its use 

 on cotton in 1872; Le Baron suggested its use 

 for the canker-worm in 1872. Cook advised spray- 

 ing trees in 1876; E. P. Haynes, in 1878, sprayed 

 trees for canker-worms and killed the codling moth. 

 These were the beginnings. Our insect foes are 

 increasing and we must spray. 



Some principles of spraying — Spray at the 

 right time, before rains for most fungous diseases 

 and after rains for insects alone. Watch the de- 

 velopment of buds, blossoms, fruit and weather and 

 spray accordingly and not by dates. Spray thor- 

 oughly. Every leaf and fruit should be coated. 

 Use a nozzle, in general, that gives a fine spray and 

 use at least 75 pounds pressure, but better 150 

 pounds. 



DUSTING 



Dust for control of insects and fungi may con- 

 sist of lime, dry Bordeaux and some arsenical or it 

 may consist of a mixture of sulphur and an arsen- 

 ical. These dusts were introduced to lower the 

 cost and labor of spraying. They do both but the 

 ultimate value of them rests on their efficiency. 



