PLANT LICE. 199 
cient space between them to enable the individuals to insert their 
extended beaks into the tissues of the leaf. Before long their 
black bodies also cover the leaf-stalks, the stems, and the still 
green berries. As they secrete a large amount of honey-dew, 
numerous flies are attracted, who keep up a constant buzz around 
such colonies of lice. Many lice-destroying insects are attracted, 
and these multiply so rapidly that they cause astonishing havoc 
among their defenceless victims, and if nothing happens to them 
they will before long clear the trees of the lice, which, however, 
appear a second time later in the season, when they only occupy 
the more terminal leaves. 
The species is sometimes exceedingly numerous, hence cor- 
respondingly injurious if not combatted by beneficial insects or by 
the energetic owner of the trees. 
Myzus ribis Linn. (The Currant Plant-louse). 
This plant-louse (Fig. 134, Plate IX) is only too common 
in our state, and frequently becomes so numerous as to cause con- 
siderable damage. In some gardens it is not uncommon to see 
the different varieties of currants, and to a less extent the goose- 
berries, with every leaf distorted by them. Early in spring the 
stem-mothers settle, usually singly, upon the under side of a still 
very young leaf, sometimes not yet fully expanded, and insert 
their beak to obtain the liquid sap from it. This causes the leaf 
to distort in such a manner that a discolored, bladder-like hollow 
is formed, in which the louse, and later the numerous offspring, 
are well sheltered, and where they can not readily be reached by 
sprays applied to kill them. The bladder-like distortion assumes 
a dark red color and is readily detected. The lice themselves 
have a shining black head and thorax; the abdomen is pale green 
or yellowish green, with a large graduate patch above, the margin 
with a row of black dots. The pale, or but slightly dusky honey- 
tubes are cylindrical, sometimes widening in the middle. 
According to Webster the winged lice leave the bushes early 
in summer, but he was unable to discover to what plant they 
migrated; but in September and October winged oviparous 
females returned to the currants and gave birth to young, who 
developed into oviparous females. The winged males flew in 
