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MISC. PUBLICATION 62 6, U. S. DEPT. OF AGRICULTURE 



getting any of the mixture on the foliage 

 of the plants, for it will cause burning. 

 Drenching the infested areas with a 

 strong pyrethrum solution is useful. 



Prevention. — Rake up all dead 

 leaves and other decaying vegetation, 

 and remove stones, boards, or other 

 materials under which millipedes may 

 hide. 



EARTHWORMS 



The soil of pots and flower beds often 

 becomes overstocked with earthworms, 

 in some instances causing injury to the 

 plants. The worms may be brought in 

 with the soil or manure, and they breed 

 rapidly under favorable conditions. 

 Their habit of tunneling through the 

 fine root systems is often damaging and 

 destructive to the plants. 



Treatment. — Bichloride of mercury 

 (corrosive sublimate) is a good remedy. 

 It is prepared for use by dissolving y 2 

 ounce in 4 gallons of water, and applied 

 by saturating the infested soil. The 

 worms usually come to the surface with- 

 in a few minutes after the application 

 and should be gathered and disposed of 

 immediately to avoid any danger of 

 poisoning birds that might feed on them. 

 Since this chemical is a deadly poison 

 and may seriously burn the skin when 

 undiluted, extreme care should be 

 taken in preparing and handling it. It 

 corrodes metals, and should preferably 

 be prepared in a glass or glazed vessel, 

 which should be thoroughly cleaned 

 immediately after use. 



A saturated limewater applied to the 

 soil freely is also of value. About 2 cup- 

 fuls of unslaked lime placed in a 2-gallon 

 bucket of water, thoroughly agitated 

 and allowed to settle, will furnish the 

 desired clear liquid. This should not be 

 used around azaleas, rhododendrons, or 

 other acid-loving plants. Tobacco dust 

 thoroughly worked into the soil will 

 prove effective also, and at the same 

 time may have some value as a fertilizer. 



INSECTS ATTACKING SPECIFIC 

 PLANTS 



In this section the discussion of the 

 insects is presented under the specific 

 plant, or host, on which they are likely 

 to occur. The plants are arranged alpha- 

 betically. When a pest has been dis- 

 cussed elsewhere in the bulletin, refer- 

 ence is made to the page where the 

 information is given. 



Space limitations prevent including a 

 discussion or even a list of the many 

 kinds of plants that are used in home 

 surroundings or the flower garden. 



However, many of the annual and 

 perennial plants are subject to injury 

 by the same insects, that is, the general 

 feeders which attack a wide range of 

 plants. Some of the more common of 

 these, as well as the soil pests, are dis- 

 cussed in the preceding section on Gen- 

 eral Plant Pests, pages 2 to 18. For 

 plants not included in this bulletin, 

 therefore, the discussions in that section 

 and in the section on Insecticides, pages 

 94 to 104, will be useful for obtaining 

 information on the control of various 

 kinds of insects and related pests that 

 may occur on such plants. 



AGERATUM 

 Greenhouse Whitefly 



The greenhouse whitefly (Trialeu- 

 rodes vaporariorum (Westw.)) feeds in 

 both the immature and adult stages by 

 sucking the plant juices. Heavy feed- 

 ing gives the infested leaves a mottled 

 appearance or causes them to turn yel- 

 low and die. The sticky honeydew 

 liquid excreted by the insect often 

 glazes the lower leaves and permits the 

 development of black sooty mold on the 

 surface, thus detracting from the beauty 

 of the plants. This insect is chiefly a 

 pest in greenhouses, but at times it 

 attacks outdoor plants. This is espe- 

 cially true of those growing near infested 

 greenhouses or conservatories or in 

 flower gardens where infested plants 

 have unknowingly been set out. The 

 species has been recorded on many 

 kinds of plants, but is most frequently 

 found on ageratum, aster, calendula, 

 coleus, goldenglow, and lantana. 



The adult (fig. 31) has four wings, is 

 about Me inch long, and the wings and 



Figure 31. — Adults of the greenhouse 

 whitefly, male and female. About 8 

 times natural size. 



