12 SECOND REPORT ON ECONOMIC BIOLOGY. 



LIFE-HISTORY. 



The eggs are laid on the underside of the leaves of such plants as 

 Cabbage, Beet, Pea, Bean, etc. The larvae hatch out in about four- 

 teen days and commence feeding upon the leaves. When full-fed 

 they are a delicate green, with short, almost colourless hairs, and 

 have six white wavy lines running down the back. At each side of 

 the body is a yellowish and more conspicuous stripe, with an indistinct, 

 broken line below it. Pupation takes place in the plant. After about 

 a month from hatching the larva spins a cocoon in a leaf or on the 

 stem, and changes to a deep black-coloured pupa. The moth appears 

 twelve to fourteen days later. There are two or more broods annually. 



PREVENTIVE AND REMEDIAL MEASURES. 



In gardens and small plots, handpicking will prove effective. 

 Fowls greedily devour the larvae. 



All grass-grown or weedy spots in or near to gardens should be 

 cleared, especially nettles and thistles. 



Watering with liquid manure I found answer very well where the 

 larvae were very plentiful on cabbages. 



Dusting the plants with equal parts of lime and soot as soon as 

 the larvae are noticed is also serviceable. 



THE BROWN CHINA MARKS MOTH. 



Hydrocampa nymphaeata. 



In June last leaves of Nymphaea alba, Linn., were received from a 

 firm of horticulturists, which on examination were found to have a 

 number of oval pieces bitten out of them. Upon examining the tanks 

 in which the plants were growing numerous pieces of the leaves were 

 found attached to the upper surface of the leaves by silk threads, and 

 in other cases two oval-shaped pieces of the leaf were attached to 

 each other. On separating these, a yellowish-white caterpillar, about 

 an inch in length was found inside. The head was brownish-black 

 and partly retractile, and the whole of the body covered with a series 

 of minute, closely-set prominences. 



Reaumur was the first to notice and describe this interesting 



