232 



THE HAWTHORN. 



wards serve as food for the ravenous larvae of the 

 parasitic insect. Small birds, especially the much 

 calumniated, but really valuable, tom-tit, eagerly 

 devour them soon after they are hatched, as well 

 as in the following spring when they are dispersed 

 upon the shoots, and even break open and rifle 

 the habitations in which they had so carefully 

 ensconced themselves for the winter. Owing to 

 these united causes, the number of those which 

 survive till the spring is very limited,; so that it 

 is only when their natural enemies, the birds and 

 above-mentioned insects, have been destroyed, 

 either by natural causes or by human agency, 

 that their ravages are seriously to be apprehended. 



Another insect which frequents the Hawthorn 

 and several of our forest and fruit trees, is the 



Yellow- tailed Moth" {Bombyx, or Forthesia^ 

 chri/sorhoed). The caterpillar of this insect closely 

 resembles that of the Hawthorn-butterflj^, differ- 

 ing principally in having two reddish-yellow tu- 

 bercles near the extremity of the body, and four 

 near the head. Its habits, too, are very similar : 

 but its winter quarters are somewhat more com- 

 plicated, consisting of several leaves, and divided 

 into chambers. The caterpillars of this species 

 are preyed on by small birds to a less extent than 

 those of the last-mentioned, owing, it is conjec- 

 tured, to the thick hairs on their backs ; but their 

 excessive increase is checked by a very small fly, 

 scarcely visible to the human eye, which lays its 

 eggs singly in the eggs of the Yellow-tailed 

 Moth, so that, instead of a caterpillar, the larva 

 of a fly is produced, which makes use of the 

 egg for its food, and the shell for its dwelling. 

 Field-bugs and Ichneumon-flies are also appoint- 



