18 BULLETIN 1357, U. S. DEPARTMENT OF AGRICULTURE 
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. 
Captive beetles, in glass vials closed with cork, have deposited eggs 
on green leaves, in 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 cn the glass when a leaf rests 
against it. These beetles, however, have shown a preterence for dry 
leaves when such have been kept in the vials. | 
Observations on egg deposition in cages and in the greenhouse dur- 
ing three successive years 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 vary from these results. 
TABLE 8.—Number of eggs per mass in egg masses of the strawberry rootiworm 
beetle 
Number of— Number of— a We Number of— 
E E g 
Eggs per mass «Bee Eggs per mass aces Eggs per mass Eeed 
ie Lee ae gee me SIM Sos ata Si Deve ee 50: |}ibbs:: 2 sae 1oe Sore geen cee 3 
y aN Me Se Pee Ec TGC SG see A aes Fae Foe D4. WOUG Soe =e ee ee eee Z 
3a ee eee a ee A648 fat) ON NR ES de LO, DAU Devan Seat SS ia es ale 3 
2b SS a pes ey ace Tt Ne 22 + Lilies 2s Se ie ae TS 11 Oe oes oe re 5 
| Ge Lia elie Mat Meee 14 SS 1D Soh ee ee To} 19" 5 Ae ee 1 
| Ge ee og Sed OE Sg ee 123 Gaels 22 eee eee Aull 20 2.) Wo ee eee 1 
ui Weenie Ss He Se 16a 148 oe ee ee S21}: 28.) sae en ee eee 1 
i) 
| 
| 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 day or later. The tips 
of the mandibles begin to show as they 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 indfviduals 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 
given in Tables 9 and 10. ; 
