Packard.] RELATIONS OF INSECTS TO MAN. 
73 
divested its old skin of its coat of dust, in order to recover 
itself therewith.” 
Does the bed-bug poison us when it bites? So we may 
ask whether the flea, mosquito and black fly, convey a drop 
of poison into the punctured wound they make. This is a 
disputed point. Dr. Landois, however, the latest writer on 
this subject, thinks that “when the creature is sucking, a 
part of the salivary fluid can easily pass into the wound, 
and it is not unlikely that the red stains that we often see 
appearing after a sting on the hands of sensitive persons 
originate from the saliva which flows into the wound and 
acts as a poison. ” Other hemipterous insects, he adds, are 
dreaded on account of their sting. ‘ 4 Cimex nemorum, accord¬ 
ing to Kirby, stings as powerfully as a wasp, and Notonecta 
glauca stings with a burning sensation.” St. Pierre found in 
the Mauritius bugs whose sting was as poisonous as that of 
a scorpion, giving rise to swellings the size of a dove’s egg 
and which lasted for five days. 
Another sort of bug is sometimes, according to Mr. Riley, 
found in beds in the western states. It is the Conorhinus 
sanguisuga. It is much larger than the common bed-bug, 
and its bite is much more painful. It belongs to quite a 
different group of hemipterous insects and is allied to the 
Reduvius of which we have spoken. 
Passing by the flea and the itch mites, which end the list 
of human parasites, and whose habits and appearance are so 
well known, we will dwell for a few moments on the poison¬ 
ous insects which trouble man. The poison of all insects, 
judging from the chemical composition of that of a few kinds 
which has been analyzed, is alkaline in its nature, and has 
for its main ingredient formic acid, a substance peculiar to 
the secretions of insects. 
The sting of the bee is simply a modified form of the ovi¬ 
positor of the ichneumon fly (Fig. 58, from Figuier) and 
the saw of the saw fly. It is composed of three pairs of 
9 
