GARDEN INSECTS. 35 



in the adult stage, when it becomes our common black spotted, white 

 cabbage butterfly. It is correctly known as the Imported cabbage 

 worm, as it is an old European pest. It was first introduced into 

 America near Montreal and appeared in New England in 1865, 

 whence it has spread to all parts of the United States. The butter- 

 flies are among the first to appear in the spring and lay their eggs 

 on the early cabbage. These hatch in about a week, and after 

 feeding most voraciously the caterpillars become full grown two 

 weeks later when they transform to chrysalides attached to the 

 leaves. In summer the butterflies emerge in one to two weeks, 

 but the fall chrysalides remain undeveloped until the following 

 spring. Three generations probably occur here. The caterpillars 

 attack not only cabbage but cauliflower and other cruciferous 

 crops. Often cabbage is so injured as to make it unmarketable. 

 It is evident that allowing old leaves and stumps to which the chry- 

 salides may be attached to remain in the fields over winter will 

 aid the increase of the pest. Possibly the best method of control 

 is to spray the young plants with arsenate of lead, one ounce to a 

 gallon of water, and keep the foliage covered until they commence 

 to head up well. Water heated to 130 degrees F. will destroy all 

 worms which it hits without injury to the plants. In many sections 

 this pest is not as much feared as formerly owing to the very effective 

 work of its natural parasitic enemies in destroying it. 



Another cabbage pest which is often held in check by small 

 parasitic flies is the cabbage aphis. In dry warm weather these 

 enemies are most active and consequently injury by the aphis is 

 least severe. Aphides which are distended, inflated, and dried, 

 of a brown color, and many with regular round holes in them, have 

 been parasitized. Whenever a considerable number of these occur 

 it is probable that the parasites will increase with sufiicient rapidity 

 to control the pest, and its destruction had best be left to them, for 

 destruction of the aphides by spraying would also kill the parasites. 



The relation of parasites to insects is a matter which should be 

 studied by every gardener, so that he may aid rather than hinder 

 nature's insect friends. But often the cabbage aphis does serious 

 injury, cabbage-growers in Delaware reporting thousands of dollars 

 loss from it in recent years. Whale oil soap, one pound to five 

 gallons of water, sprayed on the plants with considerable force and 



