28 



stacle to the ascension of the young caterpillar ; hence they often fail of success. The 

 remedies belonging to the first class are then the surest and best ; and although it must 

 be admitted that it involves much time and labour to renew from time to time, for so 

 long a period, the tar or other sticky application, so as to make it an effectual bar to the as- 

 cent of the insect, as well as a trap for its unwary feet, still it will doubtless pay well 

 wherever the canker worm abounds, to give this matter the attention requisite to make 

 it a success. The limited powers of motioi'. possessed by the female necessarily restrict it 

 within a narrow circle ; hence it is very local in its attacks, sometimes abounding in 

 one orchard and scarcely known in another a short distance off ; it follows that when once 

 it has obtained a footing and is neglected it must multiply prodigiously. 



'Pig- 5. The canker worms moreover have natural enemies which prey upon 



them. A small mite (Nothras ovi.rorus) has been observed devouring 

 its eggs, and doubtless some of the active little birds which winter 



with us do good service in the 

 same direction. Two species of four- 

 winged flies and one species of two- 

 winged fly are known to be para- 

 sitic on these worms, and to destroy 

 numbers of them ; some of the 

 ground beetles also feed on them, ])ar- 

 ticularly the copper-spotted carab (Ca!o- 

 soma calidum) (fig 5), and its ally with 

 tlse goldea green wing cases and beautiful varied lined body 

 {C alosoma scrutator') {fig. Q). These active beetles may often 

 be seen mounting the trunks of the trees and carrying off 

 such soft-l)odied worms. A species of wasp {Eumenes 

 fraterna) is also said by Harris to store her cells with can- 

 ker worms as food for her young, often gathering 18 or 20 

 of them for a single cell. 



Fig 



