Insects Injurious to the Apple. 99 



upon small or curved leaves. Very often the cocoon is spun 011 

 the leaf in which the larva has tunnelled, or it may be on a fresh 

 leaf. This case is formed of very fine shiny white silk, and is made 

 in well-formed examples, as follows : a thick strand extending 

 from one branch vein to another on each side, usually parallel and 

 about 5 mm. apart. The length of these lateral strands depends 

 upon the distance of the ribs apart. I have measured some 30 mm. 

 long. The cocoon is spun between these and attached to them by 

 another strand of silk on each side. The cocoon itself is cylindrical 

 and open at each end. They may also occur with the threads 

 running from the mid rib to the edge of the leaf. The pupa is 

 pale apple-green, the front fawn-coloured and also the wing cases. 

 The third segment of the abdomen has a large apical yellow 

 patch, and the base of the fourth is also yellow, the venter pale 

 green, with the tips of the leg cases black, also the eyes. It is 

 formed a few days after the larva has commenced to build the nest. 

 It is notched in front, and behind the aritennal cases stick out as 

 two prominences. The leg cases and wing cases are long and pro- 

 minent, and there are black marks noticeable at the apices of all the 

 legs. The pupa is 3-5 mm. long. 



The pupal stage lasts from ten to twenty days. The larvae found 

 in April give rise to a brood of moths in June and July. These lay 

 their eggs again, and we find the larvae occurring in July and 

 beginning of August. They mature and give rise to a third brood 

 in September and October. This latter brood of moths hibernate, 

 but those that occur early in September, may lay eggs and produce 

 another generation of larva? which mature in the middle of October 

 and join in hibernating with the late-hatched previous brood. 



PREVENTION AND TREATMENT. 



It is extremely difficult to say what to do in such an attack, but 

 fortunately it is usually limited to a few trees, and these usually 

 pyramids and espaliers, where hand-picking can be carried out. The 

 whole life seems to be spent on the tree in a protected condition, 

 the only time the larva? are free being when they leave the tunnels 

 and commence to spin. They then take no food, and as they hatch 

 out irregularly, two broods even overlapping, nothing can be done 

 to destroy them. All we can do seems to be the rather drastic 

 measure of destroying all the leafage in September by means of a 

 strong arsenical wash and so killing the larva 1 and pupas, or constant 

 spraying with paraffin emulsion in the spring to prevent egg-laying. 



It is certainly worth while to hand-pick trees that are attacked 



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