INSECTS AND PLANTS 53 



neighbourhood ; if all the crops of maize ripen simul- 

 taneously, then Chloridea will migrate en masse to the 

 cotton-fields, but, so long as there is maize to feed on, 

 damage to the cotton crops will be relatively light. Care- 

 ful computation puts the annual toll of the boll worm, in 

 the cotton-fields of the United States, at four per cent, of 

 the value of the crop. 



The female moth lays from five hundred to three thou- 

 sand eggs, usually on cotton or maize, sometimes on 

 tobacco or tomato, and the early evening is the most 

 favoured time for so doing. In favourable weather, only 

 two or three days elapse before the larvae emerge; in 

 order to escape from the shell, the larva bites vigorously 

 at the hard membrane of the egg, till it has weakened a 

 spot sufficiently to get its head through. When once this 

 is accomplished the hole is quickly enlarged to allow the 

 larva to crawl out. The whole operation takes about a 

 quarter of an hour. A very constant and curious habit of 

 the newly emerged larva) is worthy of mention. Unlike 

 the majority of caterpillars that have just come into the 

 world, the young boll worms do not immediately seek out 

 food, at least not vegetable food ; they turn their attention 

 to the shells they have just left, and begin once more to 

 eat them. Sometimes the entire shell is eaten, at other 

 times only a portion ; but, whatever the extent of this 

 curious habit, it is uncertain what benefit is derived from 

 it by the caterpillars. When replete, after their initial 

 meal, the larvae wander afield in search of more nutritious 

 food; should ill success attend their efforts and food be 

 scarce, the caterpillars, becoming cannibal, will eat any, as 

 yet, unhatched eggs which they may encounter. When 

 first hatched the larvae are about one and a half millimetres 

 in length, and by a series of from four to six moults, when 

 they again show their cannibalistic natures by eating their 

 shed skins, they attain their full growth and a length of 

 over forty-two millimetres. The most remarkable feature 



