12 MANUAL OF VEGETABLE-GARDEN INSECTS 



References 



Riley, U. S. Ent. Rept. for 1883, pp. 119-122. 



N. Y. (Geneva) Agr. Exp. Sta. Bull. 83, pp. 667-671. 1894. 



N. Y. (Geneva) Agr. Exp. Sta. Bull. 144. 1898. 



The Diamond-Back jNIoth 



Plutella maculipennis Curtis 



In this country the diamond-back moth is rarely more than a 

 minor enemy of cabbage and related crops, but in some parts 

 of its extensive range its injuries are of considerable importance. 

 Apparently introduced from Europe some time before 1854, 

 the insect is now widely distributed throughout the United 

 States and Canada ; it also occurs in South America, Australia, 

 New Zealand, South Africa, India, Greenland and Spitzbergen. 

 It seems able to maintain itself wherever its food plants are 

 grown, whether in the tropics or in the arctic region. In Eng- 

 land the insect is also known as the turnip fly and in some parts 

 of the United States it is called the shot-hole worm. Besides 

 cabbage, cauliflower, brussels sprouts, rape, horse-radish, 

 radish, kale, mustard, turnip and water cress, the insect attacks 

 stocks, wall-flowers, sweet alyssum and candytuft. It some- 

 times becomes very troublesome on these plants in green- 

 houses. 



The diamond-back moth hibernates in the adult condition 

 hidden away under the cabbage leaves left in the field. The 

 moths appear in the spring as soon as food plants are available 

 on which to deposit their eggs. The moth (Fig. 14) has an 

 expanse of about f inch. In the male the front wings are ash- 

 colored dotted with minute dark spots and have a yellow stripe 

 outlined by a wavy dark line extending along the hind border. 

 When the wings are closed, the united yellow stripes form a row 

 of three diamond-shaped markings. In the female the front 

 wings are a nearly uniform gray. The hind wings in both sexes 



