HABITATIONS OF INSECTS. 391 



But the most curious circumstance in the history of this 

 little Arab is the mode by which it retains its tent in a per- 

 pendicular posture. This it effects partly by attaching silken 

 threads from the protuberance at the base to the surrounding 

 surface of the leaf. But being not merely a mechanician, but 

 a profound natural philosopher, well acquainted with the 

 properties of air, it has another resource when any extra- 

 ordinary violence threatens to overturn its slender turret. It 

 forms a vacuum in the protuberance at the base, and thus as 

 effectually fastens it to the leaf as if an air-pump had been 

 employed ! This vacuum is caused by the insect's retreating 

 on the least alarm up its narrow case, which its body com- 

 pletely fills, and thus leaving the space below free of air. In 

 detaching one of these cases you may easily convince yourself 

 of the fact. If you seize it suddenly while the insect is at 

 the bottom, you will find that it is readily pulled off, the 

 silken cords giving way to a very slight force ; but if, pro- 

 ceeding gently, you give the insect time to retreat, the case 

 will be held so closely to the leaf as to require a much 

 stronger effort to loosen it. As if aware that, should the air 

 get admission from below, and thus render a vacuum imprac- 

 ticable, the strongest bulwark of its fortress would be de- 

 stroyed, our little philosopher carefully avoids gnawing a 

 hole in the leaf, contenting itself with the pasturage afforded 

 by the parenchyma above the lower epidermis ; and when the 

 produce of this area is consumed, it gnaws asunder the cords 

 of its tent, and pitches it at a short distance as before. 

 Having attained its full growth, it assumes the pupa state, 

 and after a while issues out of its confinement a small brown 

 moth, with long hind legs, the Phalcena Tinea serratella of 

 Linne.^ 



Some larvae, which form their covering of pure silk, are 

 not content with a single coating, but actually envelop them- 

 selves in another, open on one side, and very much resembling 

 a cloak ; whence Reaumur called them " Teignes a fourreait 

 a manteaur What is very striking in the construction of 

 this cloak is, that the silk, instead of being woven into one 



* Goeze, Natur. Menschenleben und Vorsehung. Anderson's Recreatiom, ii. 409. 

 See above p. 12. 



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