484 
Journal of Agricultural Research voi. xxvi, No. 10 
Likewise any differences in susceptibility that might exist in the two 
Species of homworms referred to in the present paper are as yet unknown. 
Summarizing the causes of homworm septicemia, one finds that 
Bacillus sphingidis is the infecting organism and the immediate cause 
of the death of the worms. There also are predisposing causes which are 
evidently very important but which are as yet largely undetermined. 
TRANSMISSION OF THE DISEASE 
Little is known of the distribution of Bacillus sphingidis. The ease with 
which this germ is destroyed through drying and its low pathogenesis 
in nature would suggest that hornworm septicemia with the death of 
large numbers of the worms, especially during the active growing season 
of the tobacco and tomato crops, is not likely to occur. The field observa¬ 
tions indicate that the disease under these conditions does not spread 
readily and that a wholesale destruction of the worms does not take place. 
When large numbers of worms have been kept together in cages for a 
few days occasionally an infected one has been found among them. 
Little is known of what occurs in this connection during hibernation. 
From what is known of hornworm septicemia, its exciting and predis¬ 
posing’causes, its pathogenesis, and its modes of transmission, the artifi¬ 
cial use of the disease to control the losses due to the feeding larvae would 
not at the present time seem to be a justifiable economic procedure. 
DIAGNOSIS, PROGNOSIS, AND TREATMENT 
A provisional diagnosis of homworm septicemia is justified from the 
symptoms and post-mortem appearances of the disease, but a positive 
one can be made only by demonstrating the presence of Bacillus sphin¬ 
gidis in the sick or recently dead worms. In making the diagnosis 
healthy worms may be inoculated by puncture, using the tissues of larvae 
sick or recently dead of the disease, and if symptoms of homworm septi¬ 
cemia are produced and death with post-mortem changes characteristic 
of the disorder occur the disease may be strongly suspected, the diagnosis 
being confirmed by finding the causal organism of the septicemia. 
Worms which meet death simply through violence do not as a rule 
undergo post-mortem changes present in homworm septicemia. Worms 
dead of poisoning were shown the writer by one of the men at the Clarks¬ 
ville laboratory, which were accompanied by post-mortem appearances 
not unlike those accompanying this homworm disease. Upon examina¬ 
tion, however, it was found that Bacillus sphingidis was not present, 
showing that homworm septicemia was not the cause of death. Experi¬ 
mental infections by some species other than B. sphingidis are followed 
by death and post-mortem changes quite similar to those in homworm 
septicemia. Worms dead from parasitism with Apanteles congregatus Say 
have been found hanging by a proleg and discolored like those dead from 
infection with B. sphingidis. All of these conditions must be differen¬ 
tiated from the homworm disease. 
When septicemia occurs in an infection with B. sphingidis death is al¬ 
most inevitable, if not entirely so. Nothing is known definitely about 
the disease condition in the body, prior to the invasion of the blood 
stream by the infecting organism. Since only a small percentage of 
worms inoculated by the feeding method die, it is not improbable that 
in this disease some of them suffer an abnormal condition within the 
alimentary tract, from which they may recover. 
