846 
Journal of Agricultural Research voi. xxx, No. o 
According to Froggatt (10, p. 26) 
N. rujipes is known in the Pacific 
Islands as the “copra bug.” 
Inasmuch as the other beetles which 
sometimes attack smoked pork already 
have well-established common names— 
“larder beetle” and “leather beetle”— 
the writers prefer the name “ham 
beetle” for Necrobia rujipes De Geer. 
THE ADULT 
TECHNICAL DESCRIPTION 
Form oval, sides subparallel, widest at apical 
fourth. Color blue, sometimes with violaceous or 
greenish luster, legs and first five segments of anten¬ 
nae castaneous, terminal six segments of antennae 
and the trophi piceous, eyes black, venter aeneous 
black. Head rather sparsely punctured, the punc¬ 
tures large and small intermingled, median portion 
of frons and vertex with very few punctures. Pubes¬ 
cence sparse, erect, and black. Eyes finely granu¬ 
lated, with a triangular emargination approximate 
to the antennal insertion. Labrum emarginate. 
Both maxillary and labial palpi with subcylindrical, 
slightly acuminate terminal segments. Antennae 
each with eleven segments; the first thick, slightly 
bent; the second about one-third the length of first, 
equilateral; third almost twice the length of second 
but of equal thickness; fourth to eighth mutually 
equal in length, each just perceptibly wider than the 
one preceding; the eighth is transverse; ninth and 
tenth strongly transverse, subequal, about one-half 
as long as broad; the eleventh almost square. Pro- 
notum transverse, sides evenly curved from base to 
apex, basal and apical angles very obtuse, almost 
wanting, lateral cariniform margin distinct, finely 
serrulate. Surface rather sparsely set with moder¬ 
ately coarse punctures; punctures much more dense 
at sides than on disc; pubescence as on head. Scu- 
tellum small, transverse. Elytra long, suture 
closed, lateral margin finely beaded, each with nine 
distinct rows of punctures, the normally occurring 
tenth row being confused with the ninth; rows obso¬ 
lete just behind the middle, surface between punc¬ 
ture rows and of apical portion rather densely 'set 
with fine punctures from each of which a posteriorly- 
directed subrecumbent black hair arises. Under 
parts and legs rather finely and densely punctured, 
clothed with pale fulvous pubescence with a few 
longer black hairs interspersed. Legs moderately 
long, femora not greatly enlarged, tibiae straight, 
tarsi short, of five segments of which the fourth is 
very small and concealed between the lobes of the 
third, first three segments with lamelliform pads 
beneath. Claws rather long, provided at base with 
a broad toothlike appendage. Length: 3.5 to 
7 mm. 3 
In the female each of the elytral 
punctures, which are arranged in rows, 
gives rise to a stiff black hair slightly 
inclined anteriorly; in the male these 
hairs are subrecumbent and directed 
posteriorly. Other secondary sexual 
characters are absent. 
ADULT BEHAVIOR 
After the transforming insect be¬ 
comes adult, it gnaws an irregular hole 
in the wall of the pupal cell, and emer¬ 
gence occurs. The meconium is voided 
in the cocoon. Sometimes a day or two 
elapse between the time the adult be¬ 
comes fully pigmented and its escape, 
and in the case of adults emerging in 
vials they often return to the cell for 
concealment. 
Mating usually occurs pro r ptly after 
two newly emerged beetles of opposite 
sex are placed together, and is frequently 
observed during the long oviposition 
period, especially when the beetles ap¬ 
pear frightened during manipulation of 
the dishes in which they are confined. 
The forwardly directed elytral spines of 
the females doubtless materially assist 
the males, which are usually smaller 
than the females, in maintaining their 
position during copulation. 
Besides sharing in the attacks of the 
larvae upon ham and cheese, the adults 
are markedly predacious and also can¬ 
nibalistic. It is apparent that the 
beetles and their larvae can destroy an 
infestation of cheese skippers (Piophila 
casei L.) in ham, 4 and under some con¬ 
ditions, as in stores of bones, they 
probably are beneficial to the extent 
that they help destroy the maggots 
of skippers and blowflies. In the lab¬ 
oratory experiments fat bacon was a 
much less favored food for adults than 
skipper larvae. 
Even when fed daily with skipper 
maggots, ham beetles sometimes dis¬ 
member an individual of their own 
species and then proceed to devour it. 
Specimens which die naturally are usu¬ 
ally promptly eaten. The beetles have 
also been observed by the writers to 
eat the eggs and larvae of their own 
species, and where adults become very 
numerous, as has occurred in boxes of 
smoked meat under observation, their 
cannibalism is apparently responsible 
for a great reduction in the number of 
their larvae. Adults which are de¬ 
prived of food usually die in two or 
three weeks. 
During hot weather the beetles may 
be seen in slow flight about infested 
rooms. The usual mode of progression, 
however, is by rapid running. When 
roughly handled they feign death for a 
short time; as a rule they are negatively 
phototropic and quite wild, but those 
which are confined and exposed to light 
during the day and fed frequently be¬ 
come increasingly tame. On being held 
in the fingers or forceps a strong, very 
disagreeable, but transient, odor is 
emitted. 
A photograph of several ham beetles 
is shown in Plate 1, A. 
3 The writers are indebted to Edward A. Chapin for the foregoing technical description. 
4 A similar service in stored products by a clerid has been reported by G. A. Kunner (26, p.35 ), who 
stated that Thaneroclerus girodi Chevrolat apparently at times causes the complete disappearance of Lasio- 
derma serricorne Fab. from boxes of infested cigars. 
