468 



Four Species of Insects wJiich feed, 



In. 1 



litliiliiti.! 



12 3 4 5 



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that the species is two years in the larva state : he has added, " In this and 

 other respects, size and colour excepted, the larvae of the wood leopard moth 

 resemble the larvae of the willow goat " moth (Cossus Ligniperda). The 

 opinions of another contributor to the Mag. of Nat, Hist., D. G. Kerridge, 

 Ipswich, are (vol. ii. p. 290.), that the larva is not hatched before August, 

 and becomes torpid by November ; and that in this short time it cannot have 

 become fully grown ; and that it resumes feeding the following spring, and 

 attains its full growth during the summer. 



There are questions on the instincts of the larva, which are so connected 

 with the subject of pupa, that it will be fitter to notice them under this subject. 



It is known that the larva has fed in trees of the following kinds : garden 

 pear, garden service, quince, elm, ash {Mag. Nat. Hist., vol. ii. p. 66. 210. 

 291.); and apple, walnut, lime, horsechestnut, beech, birch, oak. (Rennie's 

 CoHspectus of Moths and Butterflies.) 



Pupa. The larva changes to the pupa in the tree, just beneath the bark, 

 within a thin web which it had spun. The pupa is of a pale brown colour : 

 it has a row of sharp short spines, directed backwards, upon each of its ab- 

 dominal segments. When the insect is about to change out of the pupa state 

 into the imago one, the pupa forces its way out, by a channel, to the circum- 

 ference, or nearly to it, that it had produced previously to its undergoing the 

 change from larva to pupa, by alternately contracting and lengthening itself, 

 and by the spines on its abdominal segments catching against the sides of the 

 channel ; and it is able to push hard enough to break away the bark to a suf- 

 ficient extent to admit the exit of itself in the imago state. From what is 

 stated in the Mag. of Nat. Hist., vol. ii. p. 290., it is possible that a month and a 

 few days is the term of time that the insect continues in the pupa state. Mr. 

 Mathews has communicated in his account, that he accidentally let the chisel 

 slip against the side of the larva that is the theme of that account ; and that 

 " the woimd, though but slight at first, was sufficient to cause its death after 

 it had changed to a pupa." 



There are two questions on the instincts of the larva, which a consider- 

 ation of the conditions of the pupa may so much tend to make clear, that it 

 will be better to propose them under this head. The pupa is not capable of 

 gnawing wood ; and, in the instance of the species under consideration, and 

 some other species, is not capable of retrograding along the channel that the 

 larva has gnawed, in consequence of the abdominal segments each bearing a 

 row of sharp short spines, that, on contact with the wall of the channel, would 

 prevent regression. The imago is not capable of gnawing wood, its mouth being 

 of the sucker-like kind, and called in entomology an antlia. It is opposed 

 to likeliness, that a larva should turn round in a channel that it has but gnawed 

 of dimensions sufficient to admit its own progress ; and it is opposed to en- 

 tomological rule, that an imago should come forth from the posterior end of a 



