INSECTICIDES AND EQUIPMENT FOR CONTROLLING INSECTS 39 
Do not practice the old maxim “If a little is good, more is better.” 
Excessive quantities of wetting agents may increase the run-off of 
the spray and thereby actually decrease the efficiency of the ma- 
terial. Excessive quantities of insecticide in the spray greatly 
increase the cost and may injure the plants as well as waste strategic 
materials. 
As sold by dealers in garden supplies, many spray preparations 
contain the essential ingredients in concentrated form, ready for dilu- 
tion with water and application to plants. Where only small quan- 
tities of insecticides are required, it may be more practical to use 
such prepared spray or dust mixtures than to purchase the ingredi- 
ents separately. The latter procedure is usually more economical 
in commercial practice where large quantities are used. It may be 
possible for gardeners to make group purchases of insecticides in 
larger quantities at lower prices and to mix dusts cooperatively. 
Such procedures save in cost of materials and time. 
If proprietary insecticides are used, select those labeled to show 
the active ingredients. Reliable companies have usually tested their 
products sufficiently so that confidence can be placed in their 
recommendations. 
A set of measuring spoons, measuring cups, and a gallon measure 
calibrated in pints and quarts should be provided for accurately meas- 
uring the materials. Larger utensils are of course required if con- 
siderable quantities of insecticide are to be applied. Such utensils 
should be retained for this purpose only. 
The chance of error is greater in measuring dry materials than 
in measuring liquids because of differences in compactness and density 
of different brands. Whenever possible the quantities of dry in- 
gredients should therefore be determined by weight. Before meas- 
uring a dry ingredient in small quantities, free it of lumps and com- 
pactness by stirring or screening. After filling the measure, scrape 
off the excess with a straight-edged piece of wood, such as a pot 
label. 
QUANTITY OF SPRAYS OR DUSTS TO APPLY 
Table 1 gives information on the quantities of liquid insecticides 
and dusts, such as lead arsenate, calcium arsenate, derris, nicotine 
sulfate, and other materials, that are necessary to treat row crops 
at the different rates per acre. Normally an acre of crop grown in 
rows, such as beans, potatoes, cabbage, and similarly grown plants, 
requires from 75 to 150 gallons of liquid spray, depending on such 
factors as the nature of the crop, the size of the plants, and the thick- 
ness of the growth or stand. On an average, however, from 100 to 
125 gallons of liquid spray will cover the plants in an acre satis- 
factorily. For small gardens approximately 1 to 114 quarts of 
liquid spray is needed to cover 50 feet of row for each application. 
Information is also given on the number of feet of row that 1 gallon 
of spray will cover at application rates ranging from 75 to 200 gallons 
per acre. 
With reference to the application of insecticidal dusts, an acre 
usually requires from 15 to 25 pounds per application, with an average 
of about 20 pounds. The variation is subject to the same factors 
as to crop, size of plants, thickness of the stand, and nature of the dust 
