20 The Bulletin. 



second brood average from seventy-two to eighty-four eggs each, as 

 against an average of one hundred for the over wintering brood. 



The length of time from the laying to the hatching of the eggs varies 

 from ten or eleven days in the spring to only three or four days in warm 

 summer weather. 



The Young Bugs or Nymphs. — The young bugs which hatch from the 

 eggs are of somewhat the same general shape as the adult bugs except 

 that they are perhaps a little more flattened, the body is more oval in 

 outline, and the young bug is without wings. These young bugs are 

 known as "l^ymphs.' When first hatched they are of a greenish 

 color, but later they develop much the same general colors as the parent 

 bugs, though the markings are paler. These Nymphs are active and 

 run about freely from place to place. They feed voraciously by sucking 

 the sap from the plant and do much injury in this way. The skin is 

 shed from time to time to allow for further growth, this being done 

 five separate times in the development of the young bug. In the last 

 stage of its life as a nymph the young bug has evidence of the develop- 

 ing wings in two plainly visible wing-pads on the shoulders, and when 

 the skin is shed for the fifth and last time the wings come out fully 

 developed, and after drying and hardening the insect can fly. 



At Washington Mr. F. C. Chittenden found* that it took practically 

 sixty days from the time the bug hatched from the egg to become adult 

 and get wings, — this was with bugs hatched early in the spring. And 

 Prof. Smith at Raleigh, working with bugs hatched in latter part of 

 August found that it took from fifty-seven to sixty-five days. It can 

 be said, therefore, in a general way, that it takes about two months for 

 the young bugs to get grown. • All this time they are unable to fly and 

 (unless the plant dies) they are apt to remain on the same plant. One 

 can easily understand how a brood of these young bugs, from six to 

 twelve in number (even if only one egg-mass were laid on the plant), 

 would cause very serious damage during their growth. 



While the bug is in this nymph stage the body is softer than is that 

 of the adult bugs, and is not so much protected by the wings. It is 

 while in this softer condition that we have the best opportunity to com- 

 bat them by spraying as will be explained later under head of Remedies. 



The Adult Bugs. — The adult stage has already been mentioned and is 

 quite well known to persons who have the pest to deal with. The adult 

 bug has fully developed wings ; is black, yellow and orange in color, and 

 the body is widest at the shoulders. These adult bugs also feed on the 

 plants but not so actively as the nymphs. 



Food Plants and Habits. — The Harlequin Bug feeds on most plants 

 of the cabbage family and has been recorded on a number of others. 

 Mr. Chittenden mentions them as having attacked potatoes, unripe 

 fruit of egg-plant, the pods of okra (sometimes called "gumbo") and 

 beans, beets and asparagus. It should be remembered that it is pre- 

 eminently and primarily a pest of the cabbage and related plants, and 

 seems to attack these others only when its more natural food is lacking. 



•Qrcular 103, Bureau of Entomology, "The Harlequin Cabbage Bug," p. 5. 



