May l, 1925 
The Ham Beetle 
853 
is concluded that a close, dry crevice is 
preferred by the laying females. 
INCUBATION PERIOD 
At temperatures of 70° to 85° F. the 
usual incubation period is four or five 
days. In early winter, when tempera¬ 
tures became low in the laboratory at 
night, incubation periods of two weeks 
were recorded. Batches of eggs hatched 
with uniformity as regards time; the 
last eggs to hatch produced larvae about 
one day after hatching began, in warm 
weather. Table I shows incubation 
periods observed in 1922 at Washing¬ 
ton, D. C. 
FECUNDITY 
The results of oviposition in vials 
containing stale bacon as food for the 
adults show an average of 137 eggs 
and a maximum of 312, which does 
not indicate that the ham beetle is 
unusually prolific. When the beetles 
are fed on maggots, however (see 
Table IV), a far greater capacity for 
increase is indicated, and it is in¬ 
structive to compare Table IV with 
Table II. 
The eggs laid by females fed with 
maggots of the skipper fly in several 
cases totaled over 1,000 and were 
obtained in the following manner. 
Pairs were mated shortly after emerg¬ 
ence from the cocoon and were fed 
daily, except Sunday, with three 
migrant larvae of Piophila casei, 
maggots in excess of tfyree being 
usually uneaten. The results of the 
oviposition of some of the pairs are 
given in Table III, which includes 20 
of the best records from a series of 
76 pairs. The discontinuance of 
another series of 32 pairs, mated in 
March, 1923, became necessary after 
six of the females had laid from 444 to 
1,110 eggs each. 
Table II .—Oviposition and longevity of Necrobia rufipes, 1922 
[Food: Stale fat bacon] 
! 
Pair No. a 
j 
i 1 
Total eggs laid 
Male emerged 
Male longevity 
Female emerged 
Female longevity 
Pair mated | 
Mating to oviposi¬ 
tion 
Duration of ovi¬ 
position 
End of oviposition 
to death of female 
Laboratory tempera¬ 
tures (° F.) 
Month 
s § 
3 ® 1 
8 E 
‘P >> 
^ a 
Average 
daily mean 
Minimum 
daily mean 
Days 
Days 
Days 
Days 
Days 
1_ 
312 
Feb. 23 
135 
Feb. 
23 
Feb. 27 
Feb.__ 
71 
67 
59 
2_ 
10 
Mar. 4 
Alar. 
4 
49 
Alar. 6 
24 
6 
I 1" 
Alar .. 
72 
67 
59 
3_ 
1,55 
Mar. 5 
_do 
do 
1 
A pr. _ _ 
80 
! 69 
58 
4_ 
140 
Alar. 6 
186 
Alar. 
3 
169 
Mar. 8 
1 
Alay_. 
79 
73 
67 
5 _ 
78 
Alar. 7 
160 
Alar. 
7 
160 
-.-do_ 
22 
107 
30 
June.- 
86 
79 
70 
6_ 
239 
Arar. 9 
104 
Alar. 
9 
142 
Alar. 10 
14 
97 
30 
July- 
87 
79 
71 
i __ _ 
68 
___do_ 
158 
!_do. 
175 
_ do 
Aug-_- 
83 
76 
71 
8_ 
109 
-_-do_ 
163 
---do. 
183 
-_-do_ 
26 
104 
52 
Sept__ 
81 
73 
62 
9_ 
38 
Alar. 10 
85 
Alar. 
76’ 
90 
-.-do_ 
14 
35 
41 
10_ 
111 
Alar. 11 
118 
Alar. 
11 
161 
Alar. 14 
16 
111 
31 
11_ 
233 
_.-do- 
-_-do. 
94 
..do_ 
6 
85 
0 
12_ 
192 
Alar. 13 
87 
Alar. 
76’ 
137 
---do_ 
6 
72 
55 
13_ 
94 
Alar. 15 
Alar. 
15 
Alar. 18 
24 
88 
; 
Total.-. 
1, 779 
1,196 
1,360 
152 
705 
256 
Average 
137 
133 
136 
17 
78 
32 
i 
a These pairs were used in preliminary experiments, but the results clearly show that an exclusive diet 
of smoked pork is not the most favorable food for adults kept in close confinement. Compare with Table 
