J- 



ROBERT W. HEGNER. 



Two eggs in the light and all of those- in darkness hatched on 

 June 19; the two remaining in the light hatched on June 20. On 

 June 23 two of the larva' in the darkness moulted. Three of 

 those in the light died on June 23; the other moulted on June 24, 

 as did the two remaining in the dark. All of the larva? were 

 accidentally destroyed on June 25. 



Experiment C.B. 70. Four batches of eggs were laid by four 

 different beetles at approximtaely 10:30 A.M. June 26. One 

 half of each batch were allowed to develop in the light several 

 feet from a window; the other half were placed in darkness as in 

 experiment C.B. 42. The conditions of moisture and tempera- 

 t ure were similar in the two dishes. The data have been arranged 

 in Table VI. 



TABLE VI. 



DATA RECORDED IN EXPERIMENT C.B 70. SHOWING THE RATE OF DEVELOPMENT 



OF EGGS, LARV.E AND PUP^E OF Calligrapha bigsbyana IN WHITE 



LIGHT AND IN DARKNESS. 



Date 1909. White Light. 



June 26 15 fresh eggs from 4 batches 



July i 8 A.M. 5 hatched 

 July i i P.M. 

 July 2 

 July 3 



July 4 



2 hatched 

 7 larvae 

 7 larvae 



7 larvae 



July 5 

 July 6 



July 7 



July 8 



July 18 

 July 21 

 July 22 

 July 23 

 July 26 

 July 28 

 July 29 

 July 30 



August i 



1 moulted 



4 moulted 



:i second moult 

 i still in ist instar 

 2 second moult 

 i still in ist instar 



5 ready to pupate 



2 pupae 



4 pupae 



5 pupae 

 .=; pupae 



2 adults 



3 adults 

 5 adult - 

 5 adults 



2 larva" did not pupate 



Darkness. 



1 6 fresh eggs from 4 batches 



5 hatched 

 2 hatched 



2 hatched 

 9 larvae 



f 8 larvae alive 

 I. i larva dead 



6 moulted 

 i dead 



/ i second moult 

 t i dead 



4 ready to pupate 



i pupa 



4 pupae 



5 pupae 



6 pupae 

 i adult 



3 adults 

 5 adults 



f 5 adults 



I i adult did not emerge 



Discussion and Conclusions. The eggs of C. hi^shyana are 

 attached to the under surface of the leaves of the food plant of 

 the larvse, Salix longifolia, and are thus never exposed to the 

 direct rays of the sun except for exceedingly brief intervals when 

 the leaves twist in the wind. They develop therefore in light of 



