Insects and Diseases. 171 



The TENT CATERPILLAR, or common orchard caterpillar, 

 described on p. 144, is sometimes confounded, by superficial ob- 

 servers, with another insect, known as the Fall Web-worm, which 

 hatches out, not early in the spring, but after midsummer. Both 

 make a web or tent ; but the Fall Web-worm has a wider range 

 of trees for its food. It spins a cocoon late in summer, and does 

 not come out till the following summer. The moth or miller is 

 white, and it deposits its eggs in an irregular mass on a leaf, where 

 they soon hatch and the larvae begin their work. 



FOREST TENT CATERPILLAR. This insect (Clisiocampa syl- 

 vatica) resembles in some particulars the tent caterpillar of the 

 orchard (C. americana], but differs in being less confined to nests, 

 and in the markings of the larva and moth. The middle of the back 

 of the larva is marked with a row of small spatula-shaped white 

 spots ; while in the common tent caterpillar the back has a con- 

 tinuous white line. On the perfect insects, the former is darker 

 between the bars of the wings ; on the latter the wings are lighter 

 between the bars. It appears only occasionally in large numbers. 

 In the year 1867 it was quite destructive in Western New York, 

 and received the erroneous name of "Army Worm," the true 

 army worm being a southern insect, which destroys large fields 

 of grass. 



Like the common orchard caterpillar, the miller deposits 

 its eggs in the form of a ring or cylinder, on the young twigs ; 

 but instead of the rounded form given to the mass of eggs 

 of the orchard caterpillar, the eggs of the forest caterpillar 

 form a distinct even-sized cylinder, with square ends, as in 

 Fig. 495. Each mass contains about 300 or 400 eggs. The 

 eggs are small, about the twenty-fifth of an inch long, and 

 the fiftieth part of an inch in diameter. These eggs are de- 

 posited about midsummer, and the larvae hatched early the 

 following spring. They are very hardy, and endure any 

 cold snap that follows. They commence spinning a web 

 wherever they go. 



The forest caterpillar spins a web close to the tree, but as it grows 

 larger it wanders far away, and hence is generally supposed to have 

 no web. In its travels it generally selects smooth surfaces, and 

 seems to have a special liking to the cap-boards of board-fences. 

 It often swings down on a web from trees, and when numerous in 

 forests proves quite annoying to persons traversing the woods. It 

 devours the leaves of different kinds of trees, but seems to prefer 



