INSECTS INJURIOUS IN 1902. 45 
ON ELM: Schizoneura americana, Riley. 
Observed in a few instances on Elm trees. 
ON ALDER: Schizoneura tessellata, Fitch. 
A clump of Alders on the boulevard on the west side of the 
Lake of the Isles about sixty yards from the Peavey Stone Foun- 
Fig. 42.—S. tessellata, winged and wingless individuals, much enlarged. 
tain, Minneapolis, have been badly infested this season and are 
apparently dying as a result of injury from this insect. 
This pest is commonly known as the alder blight. Like al- 
most all plant lice, it elaborates a so-called honey dew from the 
sap of the tree, which exudes from two tubes on its back, and this 
honey dew, dropping on the leaves and branches below the insect, 
forms a favorable culture for a dark fungus growth, giving that 
part of the tree a blighted appearance, and it was from this fact, 
