158 DESTRUCTIVE INSECTS OF VICTORIA: 



and having been thus disturbed, come from under the 

 leaves, where they usually lie concealed. 



The eggs of this insect, which are of a dirty white 

 colour, are deposited in large numbers on the leaves of 

 cabbages, and, in Europe, on turnips and other plants of 

 the same natural order. They may also be found 

 deposited on the sides of crates in which cabbages and 

 cauliflowers are packed for shipment. This latter is a 

 constant and fertile source of danger in the way of 

 carrying pests to and fro from one place to another, and 

 thus destructive insects are distributed broadcast through- 

 out the civilized world. 



When the young are hatched from the eggs they 

 commence to eat the young leaves. According to Mr. 

 Whitehead and others, the caterpillar stage is supposed 

 to last from twenty to twenty-eight days. Curtis, in his 

 Farm Insects, states that in the case of chrysalides kept 

 in cases the period was very irregular, ranging from ten 

 to seventeen days. My own specimens were hatched in 

 fifteen days. 



The caterpillar, when fully developed, is less than 

 half-an-inch in length, green in colour, very active, 

 wriggling about in a very erratic manner. When dis- 

 turbed they spin a silken thread (see Fig. 3) and rapidly 

 descend, or rather drop to the ground, and on reaching 

 it commence to crawl quickly away. 



The chrysalides, which adhere mostly to the under- 

 neath parts of the leaves of cabbage, are enclosed in little 

 woolly cocoons of a dirty white colour, and are often 

 very numerous, and, as Mr. Whitehead remarks, stripped 

 of the cocoon, is white or yellowish white. 



Our Fig. 4 gives an enlargement of this caterpillar ; 

 at Fig. 5 an enlargement of the moth ; and at Fig. 1 a 

 leaf of cabbage showing larvae at work, cocoons attached, 

 and holes which the caterpillars have been eating. 



With regard to the number of broods, we are, I am 

 afraid, very much in the dark, especially in the colonies, 

 as we cannot be guided altogether by information 

 gained, however carefully, in cooler countries. Climatic 



