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white wooly matter. In consequence of their work the bark 
ceases to grow wherever such clusters occur. This species has 
also a root-inhabiting form, which, like the phylloxera, causes 
gall-like growths on the smaller roots. This makes this pest a 
very difficult one to combat. 
The cabbage-aphis (Aphis brassice) occurs toward the 
latter part of the season in very large numbers on the cabbage 
and its near relatives, the rape and rutabaga. They crowd the 
under surface of the leaves, preferring the younger and more 
tender ones, and cause a curling of the leaves as well as a gen- 
eral waste of their strength. This little pest is covered with a 
waxy powder, which repels water, and thus partially protects 
the plant-louse againstsuch poisons as are applied with water. 
Kerosene-emulsion will, however, kill them if thoroughly and 
repeatedly applied. 
The aphis that inflicts the most damage to the florist and to 
the owner of the green-house is known as the green-fly. This 
delicate little pest is the cause of much, labor and expense. It 
thrives upon most of the plants grown in green-houses, caus- 
ing them to wilt and grow sickly, and often to die. 
The ash-tree is frequently infested with a leaf-louse which 
attacks its leaves at the ends of branches, and curls them very 
badly. Immense numbers of lice are produced in such curled 
leaves, where they are fairly secure from rains. Our box- 
elders are badly infested with similar insects, which spread 
over the whole tree. The willows in wind-breaks do not es- 
cape, as dark brownish-red lice occur there in immense num- 
bers, which, when crushed, give a dark reddish-purple stain. 
Wherever such insects occur in large numbers they are apt 
to coat all the leaves with the sticky honey-dew mentioned 
before. This material, if not removed by the attending ants, 
forms an excellent home for a number of lowly organized 
plants, and some of them thrive in this soil to such an extent 
that the leaf—at first simply covered with honey-dew—is soon 
hidden beneath the black colonies of such plants. We have in 
Minnesota no worse enemies to shade-trees than such lice, and 
they increase here with wonderful rapidity, owing to our un- 
usually dry summers. Being often so well protected by the 
curling of the leaves, caused by them, remedies are not easily 
applied. It ought to be the office of the park commission to 
