48 MASS. EXPERIMENT STATION BULLETIN 189. 



squirming movements from within, slips down and off the molting larva. 

 When nearly free of the old larval skin the larva easily brushes off the 

 old larval head mask, or remains of the head capsule. 



The newly molted larva is colorless, with an opaque, white head cap- 

 sule and thoracic shield. In the course of two or three hours its body 

 assumes the characteristic markings for the instar, while the head and 

 thoracic shield darken and become fully pigmented. 



After completing its emergence and coloring the larva remains quiet 

 until the body chitin becomes hard, and then resumes its activities. 



Length of Larval Life without Food. 



Newly hatched larvae of the European corn borer lived a maximum of 

 two days in life-history cages without food or water. 



Nearly full-grown larvse, isolated in glass vial cages, without food or 

 water, lived a maximum of thirty days during the active season. 



This latter characteristic is important with relation to the possible 

 transportation of infested material to localities not infested by the insect. 

 The long period of life without food would allow larvse to survive under 

 very adverse conditions, and to start new colonies of the insect when 

 opportunity afforded. 



Unusual Habits. 



Large larvse of the European corn borer will eat their way through an 

 ordinary cork stopper and escape from confinement. They are unable, 

 however, to make any impression upon a cotton plug, and are easily con- 

 fined in glass vials when these are plugged with cotton. 



Larvse also eat through paper and pasteboard. On one occasion a full- 

 grown larva, which had escaped from an indoor cage, tunneled through 

 heavy pasteboard surrounding a bottle, and pupated between the bottle 

 and its covering. 



Full-grown larvae have been observed crawling along the ground at 

 some distance from any possible food plant. In cases of necessity these 

 larvae could probably travel a considerable distance. 



Large larvse have been found underneath clods of earth and under- 

 neath rubbish in badly infested fields, due possibly to some agency which 

 forced them to leave their natural protection within the food plant. 



Infested cornstalks were buried in the soil to a depth of 6 inches during 

 the spring of 1917. Within a few days the lai-vae deserted the buried corn- 

 stalks and made their way to the surface. 



Although the larger larv^se normally feed within the plant, occasionally 

 individuals are found feeding on its exterior. This is especially true of 

 the full-grown larvse just before pupation. At this time they are fre- 

 quently found feeding on the silk and on the outer husk of the ear. 



