The Apple Mussel Scale. 
171 
exposed surface the creatures find a medium soft enough to be pene- 
trated by the suckers. Nevertheless, it is obvious that it is in 
plantations of young apple trees, and in nurseries, that the attacks 
of Mytilaspis pomorum are chiefly to be feared. Accordingly it is 
recommended : — 
1. To reject all grafts affording evidence of the presence of 
scale. 
2. To examine all grafted stocks with care, and in the case of 
such as are invaded by the parasites to vigorously scour with a 
hard brush, preferably a metallic brush, and afterwards to apply a 
liquid insecticide. This mode of treatment should be restricted to 
the winter, as, if resorted to later, the buds might be injured.- 
3. To inspect minutely any young trees it is proposed to purchase, 
and to refuse them if found to be infected. 
4. The liquid insecticides ( lotions parasiticides ) can be used at any 
period, but are specially to be recommended at the time of hatching of 
the eggs, say from the middle of May to the middle of June, when the 
larvse are still moving about, or when, only recently fixed, their protec- 
tive scale is incomplete. At the time they first attach themselves the 
creatures are so exceedingly small that the eye usually fails to detect 
them, so that measures should be in operation before the pests are 
actually visible to the unaided eye. 
5. By shaking the young trees at the time the larvse are moving 
about many of the latter will be thrown to the ground, where they 
are powerless for injury, and will probably perish. 
The liquid insecticide recommended is tobacco juice mixed with 
5 per cent, of glycerine or of treacle, the object of the latter being 
to give to the material some degree of viscosity, and to retard its 
drying up. 
From the foregoing translation of the French memoir it will be 
apparent that each scale, as it is seen upon the apple and other 
trees, shelters from 20 to 50 eggs, each of which is capable in due 
course of producing a new scale insect. The generic name Mytil- 
aspis ( fj.vTiX.os , a mussel, and ao-7ris, a shield) is in allusion to the 
shape of the scale, like that of a mussel-shell. The specific name 
pomorum (from poinum, a fruit) is suggestive of the predilection 
which the pest has for the apple tree, although it also infests pears, 
plums, hawthorns, rose trees, cotoneasters, and other rosaceous 
shrubs. In the synonym Aspidiotus concliiformis, by which the 
creature is likewise known, the generic name literally means ear- 
shield, and the specific name shell-shaped. The illustration on page 
1 G9, kindly lent by Miss E. A. Ormerod from her Manual of In- 
jurious Insects, affords faithful representations of the solitary scale, 
and of the scale-infested twig. 
The colour of the scales approximates so closely to that of the 
bark that the scales are liable to be overlooked unless close inspec- 
tion be made. Complaints of barren apple trees are, however, often 
found to be associated with the presence of this scale in enormous 
numbers ; and cultivators of the apple and allied trees would be well 
