May 1, 1925 
The Ham Beetle 
849 
The cocoon (pi. 1, D, E; pi. 2, D) may 
be completed within 24 hours, and is 
formed by filling in the open boundaries 
of the crevice chosen for pupation with 
a wall of white substance which is 
vomited at will from the mouth of the 
larva in frothy droplets. Each droplet 
appears only after the larva has chosen 
the location for the next unit of the 
wall, and it hardens into a vesicular 
mass immediately it is put in place. 
During the process of cell building 
the larva is usually curled in the cell, 
although sometimes the inclosure is 
large enough to allow it to extend its 
length. At times cocoons are broken 
into by adults and the occupants 
devoured. It sometimes happens that 
two larvae inclose themselves in a 
common cell. On one occasion a larva 
was observed to cease construction 
body axis, and the insect becomes a 
prepupa. The last larval skin is next 
cast and the pupa appears in the cell. 
The pupa is restricted in movement 
to wriggling of the abdomen, to the 
tip of which the shriveled cast skin of 
the larva usually adheres. Unpro¬ 
tected pupae are readily devoured by 
adults. Pupation occasionally takes 
place without the protection of a cell. 
The pupa is illustrated in Plate 1, F. 
DISTRIBUTION 
In 1804, Latreille (19, p. 156) gave 
the distribution of the species as 
southern France and Italy. Stephens 
in 1830 (32, p. 327-328) reported it 
rare about London, though rather 
abundant in certain years. According 
to Curtis (6, pi. 350) the range of the 
Fig. L—Map showing localities from which complaints of damage by the ham beetle (Necrobia rufipes ) 
to smoked meats have been received by the Bureau of Entomology. Records of infested cargoes landed 
at various ports are not included 
work and to remain motionless, appar¬ 
ently as a means of protection, for 
several minutes while another larva 
was crawling on the outside of the 
cocoon. Frequently, when collecting 
immature material for experimental 
use, the writers secured numbers of 
larvae by opening cells, and many of 
these were able to resume normal 
activity promptly and to secrete with¬ 
out further feeding sufficient froth to 
construct another complete pupal 
chamber. 
HE PREPUPA AND PUPA 
Several days after the cocoon is 
completed the larva contracts in 
length, the body consequently becom¬ 
ing more robust; the head assumes a 
fixed attitude at right angles to the 
insect was extensive, including southern 
France and Africa, although in Britain 
it was rare. Sharp (30, p. 254) stated 
that it is one of our most cosmopolitan 
species. Houlbert and Betis (15, p. 16) 
gave its distribution in Brittany as 
widespread, but quite rare. 
According to Lintner (20), the 
insect was introduced into the United 
States, and Froggatt (9, p. 169) 
believed the same to be true with 
respect to Australia. 
Reports of injury to smoked meats 
have been received by the Bureau of 
Entomology from Texas, Tennessee, 
Georgia, Virginia, the District of 
Columbia, Maryland, and Pennsyl¬ 
vania, as shown by Figure 1. 
In general, it may be said that 
Necrobia rufipes is a cosmopolitan 
insect. It is a species commonly 
