parallel rows cemented together in groups of about a dozen, as shown 

 in figure 1. They are normally placed on the under side of the leaves 

 and hatch, in warm weather, in three or four days after deposition 

 and in five to eight days in the cooler weather of early spring. The 

 young bugs or nymphs pass through their five stages of metamor- 

 phosis with considerable rapidity. It has been stated that the life 

 cycle could be completed in warm weather in about two weeks, but 

 this is obviously an exaggeration, as it requires four or five weeks for 

 the completion of the cycle in related insects. 



The life periods of this species were unknown until worked out 

 by Mr. H. O. Marsh, of this office. Specimens (from Texas) were 

 under observation from the first week of March until the first week 

 of May. They were under somewhat unnatural conditions, l)eing 

 confined in our office room, which was maintained during this period 

 at an average temperature of from G8° to 70° F. The first or egg 

 stage covered 11 days. The time from the hatching of the eggs until 

 the first molt gave the first larval instar or nymph period 7 days; 

 the second instar required 13 days; the third, 8 days; the fourth, 14 

 da^^s, while the fifth or pupal instar covered 17 days — a total of 70 

 days, or 10 weeks, in all, which will be not far from the maximum 

 active period of this species. The minimum will probably fall into 

 much lower figures, probably half of this time, or at most not more 

 than 42 days in extremely hot midsunnner weather. 



When cabbage and similar plants come up the insects migrate to 

 them. It has been surmised that owing to the raj^id development of 

 the cabbage bug in the South there is a possibilit}' of as many as seven 

 or eight generations each year, while in the North three or more occur. 

 The first supposition is doubtless overdrawn, as we know of no simi- 

 lar insect producing so many generations annualh'. This is a prob- 

 lem for future study. It seems probable that four or five generations 

 would be a more natural limit in the South ancl two, or possibly 

 three, in the North. 



FOOD rr.ANTS. 



In the autumn after the cabbage crop has been made and in early 

 winter, even as far north as AVashingtoii. the bugs are still afield, 

 seeming loath to seek shelter for the cold months. At this time they 

 cluster on cabbage stalks and sprouts and the leaves of turnip and like 

 plants, and when the supply of crucifers has become exhausted they 

 will attack almost any form of succulent vegetation which is most 

 available and palatable. 



On one farm the writer observed a field of 10.000 cabbage plants 

 completed ruined, which at the time of his visit, the first week in 

 October, had been deserted by the bugs. An adjoining field of pota- 



[Cir. 103] 



