CUTWORMS, ARMYWORMS, AND RELATED SPECIES 



35 



Life cycle. — Spring generation: Eggs deposited on April 14 hatched 

 in 9 days. The periods required in the various stages were as follovvs: 



Stage — Continued Period 



Instar — Continued (days) 



Sixth 12 to 23 



Stage : 

 Instar : 



First _ _ _ 



Period 

 (days) 



. 5 



Second 



Third 



3 to 4 



3 to 5 



Fourth 



Fifth 



3 to 7 



5 to 8 



Total 35 to 49 



Pupa 12 to 18 



Egg to adult 58 to 69 



Summer generation: Eggs deposited on June 30 hatched in 4 days. 

 The periods required in the various stages and the width of the head 

 capsule in the different larval instars were as follows: 



Stage : Period 



Instar: (days) 



First 3 to 9 



Second 2 to 7 



Third 2 to 9 



Fourth 2 to 10 



Fifth 2 to 21 



Sixth 2 to 21 



Seventh 10 to 27 



Width of head 

 capsule (mm.) 



0.30 to 0.35 



.50 to .62 



.80 to 1.00 



1.40 to 1.65 



2.20 to 2.60 



2.80 



Total 35 to 60 



Pupa 12 to 23 



Egg to adult 59 to 78 



Fall generation: Eggs deposited on September 17 hatched in 5 days. 

 The material was kept in an unheated outdoor insectary until Novem- 

 ber 8, when it was transferred to an unheated basement where the 

 temperature occasionally fell a few degrees below the freezing point. 

 The periods required in the various stages were as follows : 



Stage : 

 Instar: 

 First_ __ 

 Second. 

 Third__ 

 Fourth- 

 Fifth __ 



Period 



(days) 



3 to 4 



3 to 4 



4 to 5 

 4 to 7 

 6 to 8 



Stage — Continued Period 



Instar — Continued (days) 



Sixth 11 to 16 



Total 33 to 40 



Pupa 60tol07 



Eggtoadult__ 101 to 152 



The pupae were 15 to 20 mm. long and 5 to 6.5 mm. in diameter. 



Reproductive capacity. — In 12 adults that were reared and dissected, 

 the maximum number of eggs was 2,696, the minimum 1,185, and the 

 average 2,111. The fecundity of this species is greater than that of 

 any other species observed. Under favorable conditions a species 

 with such a high reproduction potential can increase quickly to out- 

 break proportions. 



Natural enemies. — Because of the fluctuations in the numbers of 

 this species in the central Great Plains, a special effort was made to 

 collect larvae in the field under conditions of both scarcity and 

 abundance. Larvae so collected were reared individually in salve tins 

 partially filled with sterilized soil, and the kind and degree of infesta- 

 tion of parasites and disease organisms were noted. A summary of 

 these results is given in table 4. 



