﻿18 



BULLETIN 1357, U. S. DEPAETMENT OF AGEICULTUEE 



is heavy, eggs may be found in 50 per cent of the dead leaves still 

 clinging to the plants. In one instance two egg masses were noticed 

 between the petals of half-opened buds, and in two other cases egg 

 masses were discovered inside of flattened straw in the manure mulch. 

 CaptiA^e beetles, in glass vials closed with cork, have deposited eggs 

 on green leaves, iii crevices of the cork, and in practically any place 

 where there were two contiguous surfaces ; eggs have even been laid 

 between the cork and the glass or on the glass when a leaf rests 

 against it. These beetles, however, have shown a preference for dvj 

 leaves when such have been kept in the vials. 



Observations on egg deposition in cages and in the greenhouse dur- 

 ing three successive j^ears gave a maximum of 23 eggs per mass. The 

 data presented in Table 8 indicate that this number is exceptional, 

 and that more of the egg masses contain 2 to 5 than 6 to 10 eggs. Al- 

 though these figures are based on deposition by caged beetles, egg 

 masses collected in the greenhouse did not var}^ from these results. 



Table S. — Num'bc?' of eggs per mass in egg masses of the strawVerry roottoorm 



beetle 



Xumber of- 



Number of- 



Number of— 





Eggs 



per 



mass 



Egg 

 masses 





Eggs per mass 



Egg 

 masses 





E 



ggs per mass 



Egg 

 masses 



1 









81 

 167 

 258 

 212 

 141 

 123 



76 



8 





50 

 24 

 24 



11 

 11 

 4 

 8 



15. 



: 16. 



17. 

 18_ 

 19. 

 20_ 

 23. 



-- 





3 



■0 



Q 





' 2 



^ 



10 _ 

 11. 

 ]2_ 

 13 _ 

 14. 





.: 3 



4.- 

 5 





5 

 1 



-6.. 



7-. 





1 

 1 



DEVELOPMENT 



The first signs of development are noted as the ends of the egg 

 become translucent 36 to 60 hours after deposition. Segmentation 

 becomes indistinctly visible about the seventh d&j or later. The tips 

 of the mandibles begin to show as the}^ become chitinized about the 

 eighth day. At this time the embryonic larva is nearly developed 

 and within 24 hours the larva breaks the shell. 



The period of incubation was usually from 7 to 18 days in length, 

 although a few individuals hatched in 4 days and a few others not 

 until 27 days, the length of time depending on seasonal conditions. 

 The reasons why the records for 1921 varied from those of 1920 are 

 unknown, and in order to check these results the incubation periods 

 of large numbers of eggs were observed during 1922. These data are 

 oiven in Tables 9 and 10. 



