INSECTS IN RELATION TO PLANTS. 543 



different willows, for instance, of Salix alba ; S. tipuliformis in the 

 pith of the stem of the red currant (Ribes rubrum, Lin. *). It is, 

 lastly, very generally known that the caterpillar of the goat moth 

 (Cossus ligniperda) lives for several years in the stems of old willows, 

 where by degrees it transforms the internal dead part into powder. 



Among the other orders we are acquainted with the family of the 

 Sirices, which all live as larvae in the stem partly of pines and partly 

 of oaks, and there change into pupae, as well as individual genera of 

 bees, for instance, Xylocopa, which bores into wood, especially door- 

 posts and gates, and there forms cells for its young*. The same in 

 the Dipterous family of the Xylophagi, the larvae of which live in stems 

 beneath the bark. 



304. 



The leaves of plants and their young germens or eyes are more 

 universally destroyed by insects. Among those which make the just 

 developing eyes their dwelling place are the larvae of the Tortrlces and 

 the skip-jacks (Haliicce). Many plants are absolutely infested by these 

 inimical guests, and we frequently hear the gardener and farmer com- 

 plain of these terrible enemies of their fruit harvest, when they have 

 resumed their activity in the destruction of the young buds. The larvae 

 of the Tortrices fold up by their webs the just developed leaves, and 

 thus obstruct the younger ones, and then conveniently eat away the 

 innermost core of the eye, which in fruit trees consists especially of the 

 blossom buds. They do not appear to have any particular preference 

 among the different kinds of fruit, but attack all at the same time or 

 successively. The skip-jacks do not weave the leaves together, but 

 merely devour the young shoots. Among these also no species appears 

 to be especially restricted to one and the same plant, but choose 

 them at caprice. Yet H. oleracea and H. nemorum, being the most 

 common species, are the most notorious. The first especially attacks 

 young culinary plants, particularly those belonging to the family of the 

 Crucifera, namely, cabbage, turnip, mustard, rape, &c. H. concinna 

 lives in the young shoots and buds of the hop ; H. nemorum in the 

 turnip; and the remaining numerous species in the buds of wild 

 uncultivated plants- 



The host of insects that destroy the leaves of vegetables is so innu- 



* Ochsenheimer Schmetterlinge von Europa, vol. ii. p. 121, &c. 



