116 
stock and as a diluent, but if it is not obtainable the water may be 
softened by adding lye or sal-soda. The emulsion should be ap¬ 
plied to plants in a fine mistlike spray with a spray-pump. 
Owing to the jumping habit of the leaf-hoppers it has been sug¬ 
gested that they be trapped by the use of fly-paper or sticky or 
greased cloth, which for convenience may be attached to frames. 
It is thought that the insects, when disturbed, will jump into the 
properly placed traps. This method should be tried early in the 
morning or late in the afternoon, at which times leaf-hoppers are 
less active than in the middle of the day. 
• 
Aphids, or Plant-lice 
A phi did a? 
(a) Aerial Species 
Greenhouse plants are injured by a number of species of plant- 
lice, but as the life histories of these insects and the remedies used 
in combating them are practically the same, it will suffice, from 
the economic standpoint, simply to enumerate the various species 
and to treat them as a class. 
Fig. 28. Black Chrysanthemum Aphis, 
Macrosiphum sanbor?ii, wingless viviparous 
female. Length about one twelfth inch. 
The Species and their Pood Plants. —Two of the most trouble¬ 
some plant-lice are the black aphis, or so-called “black fly" ( Macro¬ 
siphum sanborni Gill.), and green aphis ( Aphis rufoniaculata 
Wils.) of the chrysanthemum. (Fig. 28, 29, 30.) Both species 
are monophagous, feeding only on chrysanthemum, and usually 
