482 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



Minute hymenopterous parasites and other enemies aid in 

 controlling this pest, but it is sometimes necessary to spray 

 with arsenate of lead, two or three pounds to thirty gallons of 

 water. Where the insect is troublesome the spraying should be 

 done early and repeated as often as is necessary to protect the 

 plants until the heads form. If the fields are well cleaned many 

 of the over-wintering pupse will be destroyed. The same meas- 

 ures should be used for the control of any of the other leaf- 

 feeding larvae, and for the flea-beetles and others that often 

 attack the cabbage. 



The Harlequin Cabbage -bug (Murgantia histrionica). 

 These bright-colored cabbage-bugs, or calico-backs, or fire- 

 bugs, are often found feeding on the cabbage, where they do 

 much damage, particularly to young plants, by sucking the 

 sap from them. The adults, which hibernate in rubbish, be- 

 come active very early in the spring. This has suggested the 

 use of trap-crops such as kale, which may be planted early so 

 that the bugs may feed on it and be destroyed there by spray- 

 ing with kerosene before the cabbages are planted. The young, 

 or nymphs, may be destroyed on the cabbage by spraying with 

 strong kerosene emulsion or whale-oil soap. If a field is kept 

 clean during the winter, so that the insects will have few places 

 in which to hibernate, they will usually not become destruc- 

 tively abundant. 



The Cabbage Aphis (Aphis brassica). These little green- 

 ish aphids are nearly always more or less abundant on the 

 cabbage, but usually little damage is done except to the 

 young plants. Any of the contact insecticides, such as kero- 

 sene emulsion, or whale-oil soap, or tobacco extract, will 

 destroy the aphids if it is applied with considerable force. 

 Again, clean culture is the most successful means for combat- 

 ting this garden pest, for if all of the refuse is destroyed in the 

 field the over-wintering insects will perish 



The Cabbage -maggot (Pegomyia brassicce). The roots of 

 cabbage, cauliflower and radishes are frequently tunneled by 

 small whitish, footless maggots which are sometimes so numer- 

 ous that they seriously weaken or kill the plant. The adults 

 are small flies that look much like the common house-fly, but 



