THE ORIENTAL MOTH AND ITS CONTROL 



s 01 mi/ oneiitai inoLii < 

 b, newlv hatched larvae 



I 

 Egg- 



The female lays its eggs on the undersides of leaves (fig. 2, a), 

 usually singly. The eggs are oval, flattened, about one sixteenth inch 

 in length, with one side in contact with the leaf, and colorless until the 

 developing embryos within become evident through the transparent 

 walls. In confinement, a moth has laid as many as 551 eggs, and dis- 

 sections of other females indicate that some may lay nearly 1,000 eggs. 



When the white, semitransparent larva (fig. 2, h) issues from the 

 egg, through an opening that it makes in the shell, it is slightly less 

 than one sixteenth inch long. It molts once before beginning to feed, 



and later, as it in- ^ 



creases in size, it casts 

 its skin 5 or 6 times 

 more before becoming 

 fully grown. With 

 each succeeding molt 

 the larva takes on a 

 greater variety of col- 

 ors, and when mature 

 it presents a very 

 striking appearance, 

 with markings of yel- 

 low, blue, green, and 

 purple. These mark- 

 ings include a purple 

 area on the upper sur- 

 face, shaped some- 

 what like a dumbbell. 



At first the larva eats only small patches of green tissue from the 

 undersurface of the leaf (fig. 3), leaving the upper surface intact; 

 but as it gets older it eats the whole leaf, except the large veins. Its 

 method of moving about resembles that of the garden slug (Agrioli- 

 max agrestis L.), but in appearance it is very different from the 

 slug, because of its color and the spiny horns on its back. When the 

 larva is disturbed, it has the habit of raising its anterior and posterior 

 extremities and if, when it does this, the spiny horns come in contact 

 with a person's skin, local poisoning or irritation is likely to result, 

 the intensity of the irritation depending on the sensitiveness of the 

 part of the skin touched by the spines and upon the individual's 

 susceptibility to such poisoning. 



When fully grown the larva is about seven eighths inch in length 

 (fig. 4, a). It now ceases feeding and moves from the leaf to some 

 point on the bark of the tree, usually a fork or crotch of a twig or 

 branch, where it forms its cocoon. The cocoon (fig. 4, b) is elliptical, 

 smooth, and hard, with one side firmly attached to the bark. It is 

 grayish brown, usually with peculiar white markings, and resembles 

 a small bird's egg. 



In constructing the cocoon the larva first spins a loose network of 

 threads around itself and attaches them to the bark. Within this 

 network it continues to spin its silken thread, gradually weaving the 

 cocoon by moving its head from side to side along the lines of a fig- 

 ure 8. As the threads come close together the larva apparently se- 

 cretes from its mouth a liquid which fills the spaces between the 

 threads and hardens, producing the hard, dense wall of the cocoon. 



