1869.] RITCHIE — ON PIERIS RAP^. 297 



tural Society, Senator A. B. Dickinson gave it as his deliberate 

 opinion that the writings of Dr. Fitch had saved, annually, to 

 the single State of New York, the large sum of fifty thousand 

 dollars; and, so far as appears from the record, not a single 

 dissentient voice was raised against this most remarkable 

 assertion." The article concludes thus: — "Surely Canada, 

 with her world-renowned Geological Survey, cannot long afford 

 to neglect the encouragement of this most utilitarian pursuit." 



As all farmers and agriculturists are not likely to become 

 Entomologists, it is the duty of Natural History Societies to 

 spread such knowledge as they possess regarding insects and 

 their habits, their benefits or injuries, direct or indirect, so 

 that the benefits from insects may be reaped, and the injuries 

 averted. 



The following means are suggested for keeping in check the 

 cabbage butterfly : — As has been shown, the insect produces 

 two broods a year, which appears, first, as eggs; secondly, as 

 larvae, or caterpillars; then as chrysalides; and, lastly, appears 

 the imago, or butterfly. In the egg state of these insects little 

 can be done to eradicate them. The larval state of most 

 butterflies consists of four or five periods, or ages." When 

 they come out of the egg they immediately commence eating 

 till the first skin is too small for the body. They cast this 

 skin, a new one having been formed underneath the old one. 

 This takes place during the other periods, until they arrive 

 at full growth. The caterpillar state afibrds opportunities for 

 thinning them out by what is called hand-picking. It would 

 not be a hard matter to pick them off cabbages in a small 

 garden, but, when fields containing acres are to be taken into 

 account, the task becomes very different, although hand-picking 

 has been very beneficial, as the following instance will show. 



In the transactions of the Entomological Society of London 

 appears the following: — "A striking instance of the use of 

 hand-picking (in most cases by far the most effective mode of 

 getting rid of insects) appeared in the West Briton, a Provincial 

 paper, in 1838, stating that Mr. G. Pearce, of Penmare Goran, 

 had saved an acre and a half of turnips, sown to replace 

 wheat destroyed by the wire worm, and attacked by hosts of 

 their larvae, by setting boys to collect them, who, at the rate 

 of three halfpence per hundred, gathered 18,000, as many as 

 fifty having been taken from one turnip.'* 



"Vol. IY. U ifo. 3. 



