HANDBOOK OX IXSECT ENEMIES OF FLOWERS AXD SHRUBS 103 



and household sprays. Most of these 

 sprays are rather specific in their toxic 

 or killing action against certain insects 

 and mites. They are especially useful 

 against red spiders, scale insects, mealy- 

 bugs, aphids, and certain species of 

 thrips. They are more likely to injure 

 certain plants than are nicotine, pyre- 

 thrum, derris, or cube sprays, although 

 thiocyanates are comparatively harm- 

 less to human beings. Some of the 

 thiocyanate preparations now available 

 on the market contain other toxic 

 ingredients, as pyrethrum, derris, and 

 pine oil. Some preparations must be 

 used with a suitable wetting and spread- 

 ing agent, whereas others already have 

 these in the mixtures as purchased. 

 With some of the proprietary sprays 

 it is necessary to wash or rinse the 

 treated plants soon after the spray has 

 been applied, to avoid injury from the 

 insecticide. Since there is such varia- 

 tion in the make-up of the thiocyanate 

 sprays, the directions furnished by the 

 manufacturer should be followed. 



Caution. — These compounds are 

 generally considered harmless to man, 

 although some of them are capable 

 of causing dermatitis to humans. Since 

 the hazards are not fully understood, 

 care should be exercised in handling 

 these materials. 



SPREADERS, WETTERS, AND STICKERS 



Spreaders and wetters are materials 

 that are added to insecticides to make 

 them spread over and wet the leaf 

 surface or the body of the insects to 

 which the}* are applied, and thus in- 

 crease their effectiveness. Stickers are 

 added to make the insecticide adhere to 

 the foliage. Soap is an excellent wetting 

 and spreading agent for contact insect- 

 icides but has little value as a sticker. 

 These materials are often used with lead 

 arsenate in spraying shrubs and shade 

 trees to insure a better and more lasting 

 coverage of the plant surfaces. Pow- 

 dered skim milk, calcium casemate, 

 glue, wheat flour, and soybean flour, 

 and oil emulsions are good sticking and 

 spreading agents, whereas raw linseed 

 oil and fish oil are primarily stickers. 



In recent years various sulfated and 

 sulfonated organic compounds have 

 come into use as spreading and wetting 

 agents, especially for use with such 

 contact insecticides as nicotine, pyre- 

 thrum, and derris. Some of these are 

 known under their chemical names as 

 sodium lauryl sulfate, sodium oleyl sul- 

 fate, sulfated oleic acid, and sulfonated 

 castor oil (the last one is known com- i 



mercially as turkey red oil). These 

 materials are compatible with hard 

 water and will wet smooth and waxy 

 foliage. Many of them are used in 

 dilutions of 1-1,000 or lower by volume, 

 whereas sulfonated castor oil has been 

 used with derris (p. 100) in a 1-400 

 dilution. These materials are now 

 generally available and are sold under 

 various trade names. They should be 

 used according to the dilutions and 

 recommendations of the manufacturer. 



Do not use so much of the wetting 

 agent that it will cause an excessive 

 run-off of the insecticide from the 

 sprayed plant surfaces; otherwise the 

 effectiveness of the insecticide will be 

 reduced. 



FUMIGANTS 



CARBON DISULFIDE 



Carbon disulfide, also called carbon 

 bisulfide, although ordinarily used for 

 killing insects in stored or manufactured 

 products, is also used as a soil fumigant 

 or as an emulsion in the control of 

 colonies of ants in the ground, root 

 aphids, Japanese beetle grubs, white 

 grubs, and other soil-inhabiting pests. 

 The material can be purchased at most 

 seed and drug stores. It is a clear, 

 heavy liquid with a strong and dis- 

 agreeable odor. On evaporation it 

 gives off a heavy gas which diffuses 

 through the soil. For best results this 

 soil fumigant should be applied when 

 the soil temperature is at least 60° F. 

 at a depth of 6 inches. The liquid is 

 injected into holes in the soil, the holes 

 being placed about 12 inches apart and 

 several inches deep. The holes should 

 not be closer than 8 to 12 inches from 

 the base of the plants. Pour from 1 

 to 2 teaspoonfuls of the liquid into each 

 hole, depending on the distance from 

 the plant. Immediately cover the hole 

 with soil (and tamp it down), so as to 

 confine the gas. which soon distributes 

 itself through the soil. For fallow soil, 

 where no plants are growing, use from 

 1 to 2 tablespoonfuls per hole, in holes 

 spaced 1 foot apart. 



To control ants in the soil of the lawn 

 or garden, make the holes 2 to 4 inches 

 deep and pour into each hole from 2 to 

 3 teaspoonfuls of carbon disulfide. In 

 large anthills it may be necessary to 

 make deeper holes and to pour in more 

 carbon disulfide. It is also important 

 to place the liquid below the roots of 

 the grass; otherwise the grass may be 

 killed. 



