August, '13]. DEW: FALL ARMY WORM 363 



The eggs hatch in from two to four days, usually three days, de- 

 pending upon the prevailing temperatures. The newly hatched 

 larvae make their first meal of the egg shells, avoiding the downy 

 covering, and then lie close together for two or three hours, apparently 

 resting and gaining strength before seeking other food. After the 

 rest period a wholesale migration takes place, and the larvae actively 

 search in all directions for available food tender enough for their 

 mastication. At this period of life their strength and ability to travel 

 is rem.arkable, Mr. W. F. Turner having observed such larvae to travel 

 a distance of 15^ feet in one hour. 



As soon as the young find suitable food, the general migration 

 ceases and the larvae settle down to feed upon the plant tissues, skele- 

 tonizing the tenderest foliage that is to be found. In about 24 hours 

 the caterpillars cast their skins entering the second stage of their 

 development, there being little difference except an increase in size. 

 In another 36 hours the skin is cast again and now the marks which 

 are typical of the full grown larva begin to appear faintly. In this 

 third larval stage the specimens are about one half inch in length, 

 are -quite active and voracious feeders. The time spent in this stage 

 is about 40 hours, the stripes and marks becoming more prominent 

 before the skin is cast the third time. The fourth stage, lasting 

 usually two and one half to three days is especially prominent because 

 of the attainment of the typical marks and stripes of the full grown 

 worm and the distinct appearance of the inverted "Y" in the face. 

 There is scarcely any difference in appearance of larvae of the fourth 

 and fifth stages except in size and length. After casting their skin 

 the fourth time, the larvae attain a length of about seven eights of 

 an inch. 



During the fifth and sixth or last larval stage, the greatest damage 

 is done. The worms are voracious feeders and appear to be unusually 

 resistant to the effects of arsenical poisons. The fifth and sixth 

 stages extend over a period of seven days when the larvae, usually 

 one and one fourth inches long, enter the soil near their food plant 

 and form cells in which the transformation to pupae takes place. 

 In a stiff clay soil the pupal cells are usually three fourths of an inch 

 long and lie at an angle one half inch below the surface. In loose 

 sandy or loamy soils the cells are usually one inch long and are buried 

 to a depth of one inch. 



After the pupal cells are formed, the larvae spin a weak cocoon 

 composed of coarse silk binding together particles of soil. While 

 the process of cell formation is going on, a gradual change takes 

 place in the larva and at the end of 36 hours the pupa, varying from 

 five eighths to three fourths of an inch in length, is complete, lying 



