THE INSECT WORLD. 



361 



Cabbage-maggot, Phorbia brassiccp. — a, larva ; b, pupa 

 c, adult ; d, its head ; e, antenna. 



injurious to cabbage and cauliflower, as well as to onions, rad- 

 ishes, turnips, beets, and other root crops, while other species 

 attack planted seeds 



like those of melons ^'^- 4i9- 



and even corn. Oc- 

 casionally, instead of 

 attacking roots, the 

 maggots are found 

 boring in thick or 

 fleshy leaves, and 

 then they make 

 mines or galleries be- 

 tween the upper and 

 lower surfaces, often 

 doing much injury. 

 Sometimes their hab- 

 its are more like 

 those of the house- 

 fly, and the larvae are 

 scavengers, while a 

 few have been recorded as parasites on other insects. The 

 group, therefore, is one with diverse habits, but usually to be 

 looked upon with considerable suspicion. Perhaps the best 

 known of the root-maggots is the larva of Phorbia brassica, in- 

 festinty cabbage, cauliflower, and other plants of the same natural 

 family. Eggs are laid on the ground soon after the plants are 

 set out in the fields. The larvae make their way into them as 

 soon as they are hatched, gnawing or rather scraping the tissue, 

 so as to enable them to absorb the plant juices, for they have no 

 jaws for mastication. Decay sets in where the insects work, and 

 this favors their feeding, so in a few days they destroy the tissue 

 of the plant and stem a little below the surfoce so completely that 

 it dies. Later crops are not so much harmed, as a rule, and if 

 plants can be preserved until they reach a good size, they fre- 

 quently sustain considerable maggot attack without serious in- 

 jury. As to the best remedies against this particular insect we 

 are yet somewhat uncertain. Putting a pad or disk of tarred 

 paper on the stems of the plants when they are set out has been 

 found successful in preventing the adult from laying eggs, or the 



