Introduction. 15 



tions, and are developed in a more or less striking manner to 

 our senses, according to the force of the motive by which 

 they are governed. Some of their instincts have for their 

 object the preservation of insects from external- attack ; some 

 have reference to procuring food, and involve many remark- 

 able stratagems ; some direct their social economy, and 

 regulate the condition under which they live together either 

 in monarchies or republics, their colonizations, and their 

 migrations ; but the most' powerful instinct which belongs 

 to insects has regard to the preservation of their species. 

 We find, accordingly, that as the necessity for this preserva- 

 tion is of the utmost importance in the economy of nature, 

 so for this especial object many insects, whose offspring, 

 whether in the egg or the larva state, are peculiarly exposed 

 to danger, are endued with an almost miraculous foresight, 

 and with an ingenuity, perseverance, and unconquerable 

 industry, for the purpose of avoiding those dangers, which 

 are not to be paralleled even by the most singular efforts of 

 human contrivance. The same ingenuity which is employed 

 for protecting either eggs, or caterpillars and grubs, or pupa) 

 and chrysalides, is also exercised by many insects for their 

 own preservation against the changes of temperature to 

 which they are exposed, or against their natural enemies. 

 Many species employ those contrivances during the period 

 of their hybernation, or winter sleep. For all these purposes 

 some dig holes in the earth, and form them into cells ; others 

 build nests of extraneous substances, such as bits of wood 

 and leaves ; others roll up leaves into cases, which they close 

 with the most curious art ; others build a house of mud, 

 and line it with the cotton of trees, or the petals of the most 

 delicate flowers ; others construct cells, of secretions from 

 their own bodies ; others form cocoons, in which they 

 undergo their transformation ; and others dig subterraneous 

 galleries, which, in their complexity of arrangement, in 

 solidity, and in complete adaptation to their purposes, vie 

 with the cities of civilised man. The contrivances by which 

 insects effect these objects have been accurately observed 

 and minutely described, by patient and philosophical in- 



