304 NATURAL HISTORY OF THE FARM 
galls to grow where they make punctures with their beaks. 
On the new bark and on the leafy shoots, there are other 
aphids feeding together in great colonies, gregariously. 
These, though minute and inconspicuous in themselves, are 
readily located on new shoots because of the crinkling they 
cause the leaves to undergo. On an old neglected apple 
tree, there are apt to be many minute scale-insects scattered 
about, adherent to the bark of the green twigs. These are 
very minute and inconspicuous creatures, that appear life- 
less, indeed, but they are, by reason of the persistence of their 
attack and their very rapid rate of increase, 
among the worst enemies of the trees. 
Of caterpillars, there is a long succession 
and a great variety to be found on the apple 
tree. In spring, the tent-caterpillar spins its 
huge webs conspicuously in the crotches 
of the apple boughs. Though the tent-cater- 
Fic. 131. Oyster- Dillars will all be gone before midsummer 
ee and a new growth will be replacing the leaves 
onerealareed, eaten by them, their empty webs will still 
be seen upon neglected trees. In their stead, two other 
moth larvae, popularly known as the yellow-necked and the 
red-humped caterpillars, may be found devastating the 
foliage. Other lesser caterpillars that injure the leaves are 
the bud-moth caterpillar, that works in opening buds, the 
pistil-case-bearer that gnaws out little patches from 
the surfaces of the leaf, and the apple-leaf-miner, that 
lives within the leaf substance, making a trumpet-shaped 
blotch of a mine between upper and lower epidermis. The 
last two will be found by looking for spotted leaves that 
have their margins uninjured. 
The fruit of the apple is the place of residence for three 
insects of the sort shown in figure 6 on page 22. The larva 
of the codling-moth is a caterpillar that works in the core of 
the apple. The larva of the apple-curculio is a weevil that 
