PACKAun.] THE POPULATION OF A:N' APPLE TEEE. 171 



attached to tbe insect as at 4. By the first of August the 

 growth of the scale insect is completed, and it has the 

 appearance of an oj^ster shell, as seen at 7. By the middle 

 .of August in the western states, where Mr. Riley studied 

 its habits, the female lays her eggs, which do not hatch till 

 the following June. It will be seen that the best method 

 of warding off the attacks of this pest is to thorouglily 

 scrape the bark of the tree in the early autumn and again 

 in the beginning of June, when the 3'oang are swarming 

 over tlie surface of the bark. At this time the bark should 

 be washed with whale oil soap. But it is to the natural 

 insect parasite when reared and set loose in the orchard 

 that we are to look for the means of restraining within 

 proper limits this insect. This is the minute ichneumon fl}' 

 (Aphelinus) figured on page 42. 

 The majority of the insects injurious to the apple are found 



FEEDING ON THE LEAVES. 



The American Tent Caterjnllar^ or CJisiocampa Americana, 

 is known to every farmer's boy from the social habits of the 

 caterpillar, which lives protected from the hot sun or inclem- 

 ency of the weather under a broad tent of white silk. Not 

 very creditably to orchardists and farmers the}' are a con- 

 spicuous object at the beginning of summer, whether in the 

 New E:igland, Western or Middle states. The caterpillar 

 is easily recognized by its large size, being about two inches 

 in length, and by the long brown hairs and bright colors 

 of the body, which is yellow with numerous fine ei'inkled 

 black lines, forming low down on the sides of the body 

 a black band, with a blue spot on the side of each ring. 

 Along the middle of the back is a conspicuous white stripe. 

 It becomes full}- groAvn by the first or middle of June, the 

 period varying with its geographical position. When about 

 to make its cocoon it stops eating, and wanders restlessly 

 about in search of a suitable place in which to spin. Under 



11 



