112 THE REPORT OF THE No. 19 



broken yellow line along each side and an unbroken one down tbe middle of 

 the back (Fig. 47), are particularly destructive to mignonettes, some seasons 

 it being almost impossible to grow good plants. The insect is, however, an 

 easy one to control. The dusting of infested plants with pyrethrum insect 

 powder is about the best remedy for the caterpillars of this common butterfly. 

 This preparation can be made by mixing thoroughly one part of weight of 

 the insect powder with four parts of cheap flour, keeping the whole in a 

 closed vessel for at least 24 hours. The mixture can then be distributed eas- 

 ily by placing it in a small bag of fine muslin which can be tied to the end 

 of a short stick so that it swings freely. If the bag is tapped lightly with 

 another stick held in the other hand, many plants can be gone over quickly 

 and without tiring the operator. Many florists and seedsmen now sell proper 

 bellows or dusters for applying dry powders, and these are not very expensive. 



Fig. 48. White Cabbage butterfly. 



Fig. 47. Pontia rappe : a, caterpillar; 

 b, chrysalis. 



The Diamond-Back Moth, (Plutella macuUpennis , Curtis, Plutella cru- 

 ciferarum, Zell. (See Fig. 33.) This well-known enemy of the market gar- 

 dener, during some seasons does serious harm to wall-flowers, stocks, and other 

 crucifers. The caterpillar which is from one quarter to three-eighths of an 

 inch in length is green and very active. It is particularly abundant during 

 July and August, but fortunately occurs irregularly, being doubtless held 

 in check by parasites. These small caterpillars when disturbed run back- 

 wards, wriggling their bodies from side to side, and when they reach the 

 edge of a leaf, they let themselves down by means of a silken thread. In 

 garden practice infested plants may be sprayed with kerosene emulsion, or 

 a soap mixture, to which Paris green or some other active poison has been 

 added, the spray to be forced well up under the leaves if possible. 



The Zebra Caterpillar, Mamestra picta, Harr. (See Fig. 2.) This 

 common enemy of turnips, cabbages, clover, etc. is sometimes troublesome 

 in flower gardens. In his 1896 annual report. Dr. Fletcher spoke of a ser- 

 ious infestation at Ottawa, the plants attacked in gardens being sweet peas, 

 lilies, gladioli ; in fact it was stated that the larvae attacked indiscriminately 

 almost all the annuals. On Oct. 3rd of the present year, the writer noticed the 

 species feeding on asters. The caterpillar is a handsome one, about two inches 

 long when full grown, velvety black on the back and having two golden yel- 

 low stripes on each side of the body, which are connected by narrow lines of 

 the same colour, the head and feet bright reddish brown. When young the 

 larvse for a time feed together, but as they grow larger they separate and 

 feed singly. There are two broods of the insect in the year, the second one 

 of which occurs in September, and is the most troublesome. A remedy for 

 these caterpillars is to spray infested plants with Paris green, one ounce in 



