Packard] EELATIOXS OF INSECTS TO MAX. 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. ^'■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 Conorhhius 

 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 wliich 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 fur a few moments on the poison- 

 ous insects which trouble man. The i)oison of all insects, 

 judging from the chemical comi)osition 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 Ilguier) and 

 the saw of the saw fly. It is composed of three pairs of 



9 



