40 



MEANS OF CONTROLLING INSECTS 



should therefore be made immediately before using. 

 Particularly valuable for surface mildews. 



Maxwell Dust-Spray. — Fresh lime, 1 barrel ; copper 

 sulfate, 25 pounds ; concentrated lye, 5 pounds ; powdered 

 sulfur, 25 pounds ; Paris green, 6 pounds. 



Spread lime in a large, shallow box, breaking into as 

 small lumps as possible. Dissolve the copper sulfate in 

 six gallons boiling water; also dissolve the lye in five 

 gallons hot water. Keep separate. Sprinkle copper sulfate 

 solution over the lime. Follow with lye water. If the 

 lime does not all crumble to a dust, use clear water to 

 finish. Screen the lime through a fine sieve, rub the sulfur 

 through the sieve into the lime, add the Paris green and 

 thoroughly mix both with lime. Lime should crumble to 

 powder, not granules. 



Copper sulfate water must be used hot, or the copper 

 will recrystallize. Mixing should be done out-of-doors or 

 in a separate building, as lime in slaking becomes very 

 hot. 



Missouri Experiment Station dust-spray. (To make 70 

 pounds of stock powder): — Copper sulfate, 4 pounds; 

 quicklime, 4 pounds ; water in which to dissolve copper 

 sulfate, 2J gallons ; water in which to slake quicklime, 

 2J gallons ; air-slaked lime thoroughly sifted, 60 pounds. 



Dissolve the copper sulfate and slake quicklime 

 separately, each in 2J gallons water. Pour at same time 

 milk of lime and copper solution into a third vessel and 

 stir thoroughly. Surplus water is then strained out and 

 remaining wet material is thoroughly mixed with the 60 

 pounds of air-slaked lime. All lumps must be sifted out 

 and the mixture must be perfectly dry. One pound each 

 of sulfur and Paris green may be added. 



The dust-sprays are useful where water is scarce or 

 land is too rough or steep for the regular spraying 

 machines. 



MEANS OF CONTROLLING INSECTS 



By M. V. Slingerlarid 



Careful estimates indicate that the value of 

 farm products now destroyed each year by insects 

 in the United States aggregates the vast sum of 

 $700,000,000, or more than the entire expenditures 

 of the national government. Thus, one of the most 

 serious problems that confront the American agri- 

 culturist is that of controlling the insect enemies 

 of his crops. He is now menaced by nearly twice 

 as many different kinds of insect pests as in 1850, 

 and three or four times as many as a century ago. 

 And the outlook is far from encouraging, for all 

 the old pests will doubtless continue their ravages 

 indefinitely, with "up" and "down" periods at un- 

 certain intervals. Furthermore, the American 

 agriculturist will have the best plants and animals 

 the world produces, no matter whether he does 

 thereby Introduce other such destructive pests as 

 the San Jose scale from China. There are still 

 many insect pests in Europe, Asia, Australia, Africa 

 and Mexico that are liable to be introduced at any 

 time, and they may be much more destructive 

 here than in their native home, where their enemies 

 and surrounding conditions largely hold them in 

 check. Thus, the unbroken ranks of the insect pests 

 of a century ago will be constantly augmented by 

 new kinds that are either disturbed by man in their 

 wild haunts here (as the Colorado potato-beetle), 

 or that come in naturally from adjoining countries 

 (as the cotton boll-weevil from Mexico), or that are 



brought in by commerce from foreign lands (as the 

 cattle horn-fly and over half of the other standard 

 insect pests). 



But the outlook is not really so gloomy, for 

 the American agriculturists are well equipped 

 with insecticidal batteries, and they are waging a 

 most scientific and successful fight against in- 

 sect enemies. Many millions of dollars are being 

 spent annually in America by national and state 

 governments and by individuals in fighting insects 

 and in devising and testing new remedial meas- 

 ures ; it is estimated that over $8,000,000 is 

 expended each year in spraying apple trees for the 

 codling-moth alone. 



Natural cheeks. 



In this warfare that man must wage against his 

 insect foes, he should not forget that nature has 

 provided active and often very effective insect- 

 destroyers without which man could not grow 

 crops, or even exist himself. Were it not for the 

 many little enemies of plant-lice, these insignificant 

 creatures with their wonderful powers of multipli- 

 cation would soon overrun the earth, and destroy 

 all vegetation, thus robbing man of his primary 

 food supply. Among the forces of nature which 

 thus aid man in his insect warfare may be men- 

 tioned strong winds, sudden changes of tempera- 

 ture in winter, rains, and forest and prairie fires. 

 Then among the plants and animals there are some 

 very efficient insect-destroyers. Bacteria and fungi 

 often kill a large proportion of army-worms or 

 chinch-bugs that are devastating crops. Many of 

 the birds feed largely on insects and should be 

 encouraged to stay on every farm, for they are 

 among. the most effective of nature's insect-des- 

 troyers. 



But it is among their own kind, the insects, that 

 insect pests find their most destructive foes. Vast ' 

 numbers of insects, some so tiny that several of them 

 can live inside an insect egg (codling-moth egg) 

 not larger than a pin's head, are constantly prey- 

 ing on the insect enemies of man's crops. And 

 these parasitic and predaceous insects are often 

 very effective in aiding man in his strenuous war- 

 fare to protect his crops from insect pests. A little 

 lady-bird beetle saved the citrous industry of Cali- 

 fornia from destruction by a scale insect, and it 

 would be impossible to grow wheat successfully in 

 many sections of the United States were it not for 

 the tiny insect parasites of the hessian fly. 



Man is coming to realize more and more the 

 value of these natural aids in his warfare against 

 insect pests. In Hawaii and California, thousands 

 of dollars are expended annually in searching for 

 and importing from foreign lands beneficial insects 

 to prey on insect pests, and some striking successes 

 have been attained. Europe is now being searched 

 for the natural enemies of the gypsy and brown- 

 tail moths to aid in checking and finally controlling 

 these serious pests. 



Administrative control. 



While these insecticides of nature are often very 

 effective and finally accomplish their purpose, man 



