CATALOGUE OF INSECTS. 23 



bodied sucking insects. It has also been used against certain cater- 

 pillars and leaf beetles, but against these the arsenites are usually 

 better. A useful decoction is i lb. of tobacco refuse, chopped stems, 

 &c, to i gallon of water, boiled until a deep brown extract is ob- 

 tained. This may be used full strength or may be more or less 

 diluted according to the resisting power of the insects. Several pre- 

 pared decoctions or extracts are on the market and at least two of 

 these, i. e., Hammond's tobacco preparation, and the Rose leaf extract 

 are satisfacto^ in their effects. The Rose leaf extract is used quite 

 extensively in greenhouses, and, so far as I have learned, always with 

 good effect. In greenhouses the extract is evaporated on the hot pipes 

 and a slow fumigation is thus maintained. Details are out of place 

 here, but in general tobacco is useful chiefly against plant lice and 

 certain other forms of sucking insects as a contact poison. 



Pyrethrum, or Persian or Dalmatian powder, is too expensive for 

 field use, its range of action being fully covered by cheaper substances; 

 but in the house and small conservatory it is the cleanest and most 

 satisfactory material against plant lice, mealy bugs and similar pests. 

 Make into a decoction, or steep i ounce in i quart of hot water ; when 

 cold add a quart of cold water, using as a spray, from an atomizer 

 or the like. It is entirely harmless to plant life, but peculiarly fatal 

 to insects. 



Crude petroleum has of late been found to be especially effective 

 against armored scales hibernating as partly grown larvae, while 

 entirely harmless to dormant trees. It cannot be used in summer 

 because of its choking action among the leaves, but it may be used 

 on the bark alone at any time, and in winter the dormant tree may 

 be safely painted from crown to the surface without harm to either 

 the tree or the resulting crop. 



It can be used with an emulsion sprayer, like kerosene, and ma)' be 

 used at any time, provided only the trees are dry. 



Kerosene, one of the distillates from crude petroleum, is much 

 more dangerous to plant life, yet has a much greater range of useful- 

 ness, because it may be used in summer. Pure kerosene is fatal to 

 all insects not especially adapted to live in it, and, from its penetrating 

 character, it is more effective in reaching scale insects than any other, 

 save only the crude oil. Applied in winter on dormant trees, it evap- 

 orates rapidly under favorable conditions, and injures nothing; but 

 the margin of safet)' on peach and plum is small, and the former 

 especially are easily injured by it. In summer it may be applied undi- 

 luted in a fine spray, on a bright day favoring rapid evaporation, on 

 all except peach trees. In each case the insects are killed at practi- 



