INSECTA. 439 



be divided into two kinds ; one, where they admit of being nearly as 

 cold as the atmosphere in which they live, when they are almost per- 

 fectly inactive, requiring no nourishment : this includes most insects. 

 The other is where they cannot admit of a considerable degree of 

 diminution of their heat without suffering death : when, therefore, they 

 retain nearly their native heat, their actions are confined within smaller 

 limits ; but in such degrees of heat they always require nourishment ; 

 of this the bee is an instance. 



Insects have a great deal of blood in them while in the maggot or 

 caterpillar state. In the second change there is hardly any blood to be 

 seen ; they have but little unnecessary weight, that they may fly the 

 better. The blood of the insect is a transparent fluid. 



The blood of the large caterpillar of the privet-moth [Sphinx 

 Ligustri] appears, in the microscope, to be made up of globules floating 

 in a watery fluid. The globules are oval, but rather irregular in their 

 figure, and are pretty nearly of the same size. They seem to be very 

 numerous, and almost in contact with one another. 



The air-vessels in the maggot and caterpillar are only for the purpose 

 of respiration, and are therefore only vessels or canals : but, when 

 the chrysalis has completed its purpose, the lateral air-canal forms 

 itself into lateral air-bags, as reservoirs for air to increase the size and 

 diminish the weight of the animal for flight : from these reservoirs pass 

 the respiratory vessels to the different parts. 



Of the common Age of Insects. — I think we have reason to believe that 

 no insect lives beyond the year of its perfection ; that most insects are 

 perfected in one year, and many in the same season ; and that all insects 

 die the season they lay their eggs, whether they themselves were hatched 

 from eggs laid in that season or not. 



Every female insect does not come to perfection in the same year or 

 season in which it goes through its changes, and come to the fly state : 

 of this the bee-tribe is an instance 1 ; but, I believe, the males of this 

 tribe [do come to perfection in the same year]. 



As in many instances it will be diflicult to find out what insects live 

 through the winter, and what die, also what females live, while the 

 males die, it will be necessary to come as near to the truth as possible, 

 so as to be able to say, with some probability, that such live and such 

 die. If, for instance, we find the females, which we know to live 



1 [Hunter here refers to the labourers or sterile females of the social bees, which 

 "do not come to perfection" by reason of their abortive ovaries; although they may 

 have "gone through their changes" to the winged state. Only the queens or fertile 

 females live beyond the year of their perfection ; provided they have not laid their 

 eggs during that year.] 



