PLANT LICE. alirfal 
Schizoneura lanigera Hausmann. (The Woolly-louse of the 
Apple). 
This is one of the best known pests of the truit-grower, not 
alone in this country, but in Europe as well. Throughout the 
summer until very late in the autumn we can find in infested 
orchards small bluish-white flocculent or cottony patches produced 
by a cluster of lice, on the lower part of the trunks, but every- 
where on young trees. Such clusters are found most abundantly 
on the water-sprouts, which of course are never permitted to 
grow in orchards well taken care of. Younger trees suffer most 
severely, as in this case the bark becomes deeply pitted, in some 
cases even deep and large cavities are formed. 
“The bark apparently ceases to grow at the point of attack, 
but swells into a large ridge about the cluster of lice, leaving 
them in a sheltered pit. The lice also frequently congregate in 
the axils of leaves and the forks of branches.” (Comstock). 
As long as the lice are thus plainly visible, they can be con- 
trolled, but like the Grape-vine Phylloxera already described, 
this louse possesses a root form which is much more injurious 
and is very much more difficult to reach. On the roots it pro- 
duces gall-like swellings, in the cracks of which it lives in clus- 
tered masses. Even the deeper and more fibrous roots are in- 
vaded. The injury to the infested trees is due both to the suck- 
ing up of the sap and to the poisoning of the plants as shown 
by the abnormal growths following the injury. In cases of 
badly infested trees it will hardly ever pay to try to save them 
and to try to get rid of the lice, and it is better and cheaper 
to dig the trees up and to burn them, and to devote the ground 
to another use for some time. Of course another species of tree 
can be safely planted in the place of the one removed, but not a 
different variety of apple. 
Mr. Marlatt, in one of the excellent bulletins of the Division 
of Entomology of the Department of Agriculture, has issued a 
circular in regard to this pest in which he says that: 
“The damage is particularly serious in the case of nursery 
stock and young trees, and is less often important after the tree 
has once become well established and of some size. Where this 
insect is abundant all the roots of a young tree to the depth 
