TORTRICI.VA. 3 



from subsidence, in consequence of their soft condition at the 

 period of extrusion (Grapholitha Ulicetdna), They are sometimes 

 laid in stringy masses, as in Sphaleroptera ictericana. 



The time required for the production of the larva? after the 

 ova are deposited is unknown ; it doubtless is very varied, and 

 probably many which are laid in the height of summer remain 

 unhatched till the following spring, as must be the case with 

 Tortrix, Lozotania, and their congeners. On the other hand, 

 some must hatch almost immediately, for instance the typical 

 species of the genus Endopisa, as the larva? are found in our 

 table-peas very shortly after the appearance of the perfect insects. 



The larva state is that in which these insects perform their 

 most important offices in the economy of Nature, by checking a 

 too redundant vegetable growth, forming the food of birds, &c. 

 In fact, we look upon it as debateable ground, whether the larvae 

 of Carpocapsa pomonella, which spoil so many of our apples and 

 pears, and C. funebrana our plums, are not, while destroying 

 some of the fruit, actually improving the quality and condition 

 of the remains of the crop; for it is scarcely reasonable to 

 suppose that, if every apple, pear, or plum were to be matured, 

 the whole would be either of such size or flavour as when they 

 have undergone the natural process of thinning by these larva?. 

 By these remarks it is not intended to argue that the propaga- 

 tion of such larva? is to be encouraged, but to show that they are 

 not, as very many suppose, entirely noxious. 



Most of the larva? are leaf-eaters, and are to be found in April, 

 May and June in great abundance; the modes they adopt in 

 forming shelter for themselves, by twisting and distorting the 

 leaves and young twigs of trees, plants, &c., are so very nume- 

 rous and varied, that they can scarcely have failed to attract the 

 attention of the most unobservant. They are naked, or very 

 sparingly sprinkled with hairs, which are not always present ; 

 never found gregariously ; and, although in their young state 

 many of them are miners, none are case-bearers. 



Such as do not feed on leaves, burrow into the bark, stems, 

 roots, fruits, or seeds of their respective food-plants, Halonota, 

 Dicrorampha, Ephippiphora, Carpocapsa, &c. ; but these, as a 

 rule, are never so numerous as the leaf-eating kinds. 



The folding, twisting, or distorting the leaves and twigs is 

 accomplished by means of an elastic silk, spun by the larva?, 

 usually of a white colour, which hardens and contracts on expo- 

 sure to the air, and thus draws opposite portions of the leaves 

 towards each other. A series of spinnings and contractions 

 effects the end in view. The operation is therefore twofold : 



B 2 



