APPLE MUSSEL SCALE. 189 



like a small powdery White Moth in its appearance. 

 It may be found on different kinds of Cabbage, more 

 or less, all the year round, and towards autumn in 

 such enormous quantities that, if the plants are stirred, 

 the soft white flies will rise and float in the air, and 

 settle down like miniature snow-flakes, whence its 

 name of the Snowy Fly. They rest for the most 

 part beneath the leaves, and draw away the sap 

 with their suckers ; and at times do a good deal of 

 harm. 



As far as is known, these Snowy Flies breed in 

 winter as well as in summer. 



The female lays her eggs in a patch on a leaf; these 

 hatch in about twelve days, and the young spread 

 themselves on the leaf, and shortly become covered 

 with a scale, white, with two yellow spots. In this 

 state they much resemble the common Scale insect, 

 and they stick fast to the leaf, which they pierce with 

 their sucker. In about ten days they turn (beneath 

 this scale) to a pale chrysalis, with red eyes, and in 

 about four days more the perfect insect comes out 

 through the scale. 



The " Scale Insects," or Coccidce, are the third 

 section (distinguished as Monomera, from their feet 

 having only one joint) of the Homoptera. These 

 insects do great harm by drawing away the sap by 

 means of their suckers. 



There are many kinds, differing in various points 

 of structure, as well as form ; but in the case of the 

 Apple Mussel Scale {Aspidlotus concldformis, Curtis), 

 which is sometimes very hurtful in orchards, this 

 shell-like husk, which is in shape like a minute mus- 

 sel-shell, adheres firmly to the bark during winter ; 

 and under it, but not attached to it, there lies the dead 

 body of the female Scale, and fifty or more eggs. In 

 spring these hatch, and from them come small white 

 flat insects, furnished with eyes, horns, six legs, and 

 a sucker. These are very active at first ; but presently 

 each Scale larva runs its sucker into some spot it can 



