246 EXPERIMENTAL FARMS. 



brood were found in remarkable numbers at Ottawa during August on lucerne, and on 

 lily and gladiolus leaves. 



The eggs were much infested by two minute parasites, Trichogramma preiiosa, 

 Riley, and Telonomus sp., noticed in the same connection in 1892, and the young cater- 

 pillars were also destroyed by an Apanteles which occurred both at Ottawa and at 

 Birdsall, Ont. 



" Birdsall, Peterborough Co., Ont., August 18. — There are two kinds of caterpillars 

 which are doing a good deal of harm on my turnips, a green one and a yellow and black 

 striped one. I suppose a little of the Paris green and plaster mixture would be the best 

 thing for them. Kindly let me know if you think there would be any danger in feeding 

 roots so treated to stock." — F. Birdsall. 



" Omemee, Victoria Co., Ont., August 18. — I send you some striped caterpillars 

 which I find in numbers on the turnips, a great many together on a single leaf ; they 

 seem to eat the upper surface principally. There are with them, also abundant but 

 occurring singly, some green ones which eat the edges of the lea\*es. No. 2, and besides 

 a few of the smooth green ones with dark marks. No. 3, which feed like No. 2." — E. S. 

 Morgan. 



The green caterpillars mentioned by Mr. Birdsall and the No. 2 of Mr. Morgan's 

 sending were those of the small White Cabbage Butterfly (Pieris Rapce, L.). Mr. 

 Morgan's No. 3 were specimens of the Clover Cut-worm {Mamestra trifolii, Esp.). 



" Peterborough, Ont., September 3. — The inclosed worm is very abundant in this 

 neighbourhood this season ; it feeds on the leaves of turnips." — J. A. Fife. 



Remedies. — The best remedy for these caterpillars is spraying or dusting with 

 arsenical mixtures, but they seem to be rather resistent to the action of those poisons 

 generally used, such as Paris green. Mr. T. W. Ramm, of Ross Mount, Northumber- 

 land Co., Ont., writes : " You know the yellow-striped caterpillars of Mamestra picta 

 which are sometimes plentiful on pease. It took almost two days to kill some of these 

 which were on pease, although I almost buried them in dry Paris green of full strength 

 tested with ammonia and then it destroyed the pease as well." A weaker mixture distri- 

 buted evenly over the food plant would probably have been more fatal to the caterpillars 

 without injuring the pea plants — 1 lb. of Paris gr&n to 200 gallons of water or to 50 lbs. 

 of dry land plaster was quite satisfactory at Ottawa. 



No danger need be apprehended from feeding roots to stock which have been dusted or 

 sprayed with Paris green mixtures. There are always several weeks — and this at a rainy 

 season of the year, too — between the time that this is likely to be necessary and when the 

 roots are fed to stock. If there is any doubt, however, about all the poison being washed 

 off the roots, the tops can easily be cut off closer to the root than usual, which will 

 remove all possibility of danger. The poison could only lodge in the axils of the leaves, 

 of which a clean sweep will be made when the leaves are cut off. 



Owing to the gregarious nature of the caterpillars when young, good work can be 

 done in August and September by picking ofi" the leaves bearing the young broods and 

 destroying them. 



Small White Cabbage Butterfly (Pieris Papce, L.). — It will be noticed in the 

 above extracts that this insect was twice mentioned as injurious to turnips. There were 

 other reports of the same nature, but the chief injury mentioned by correspondents was 

 to cabbages. There are few insects more easily controlled than this, if prompt action be 

 taken at the proper time. 



The best remedy for this insect, as far as my experience goes, is undoubtedly pyre- 

 thrum powder diluted with four times its weight of common flour and then kept in a 

 tightly closed vessel for twenty-four hours until the poisonous principle has permeated 

 the whole mixture. If a small quantity of this mixture be dusted over infested plants, 

 the caterpillars are all destroyed, and in a surprisingly short time. Pyrethrum or insect 

 powder kills by contact, both in a dry condition and as a decoction, so that such cater- 

 pillars as are not actually reached by the powder are destroyed by the poisonous principle 

 of the pyrethrum carried farther among the leaves by rain or condensed dew. This 

 remedy is so eflPective and so cheap that I do not think it well to recommend any other. 



