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NEW YORK STATE MUSEUM 



transverse galleries, possibly designed to girdle the infested twig 

 partly and thus reduce its vitality. 



This species has been studied by Mr Engelhardt, who has kindly 

 placed at our disposal the following notes respecting its life history. 

 The moths begin to emerge during the last week of May but more 

 generally appear during the first half of June. Eggs are deposited 

 singly on small twigs, though on the trunks and branches of large 

 plants they occur in numbers in close proximity. The larva at first 

 attacks the inner bark, working gradually through the cambium 



layer into the sapwood, forming ir- 

 regular galleries i to 2 inches in 

 extent. Late in August the young 

 larva is about one-half grown, and 

 the last of October many may be 

 full size. The larva remains dor- 

 mant within its gallery during the 

 winter and early in the spring be- 

 gins to prepare a place for pupation. 

 This consists of a tunnel reaching 

 from a lower chamber in the sap- 

 wood, up through the outer bark, 

 leaving a thin, circular layer at the 

 opening through which the imago 

 can easily escape. The larva in- 

 closes itself in its lower chamber 

 within a slight cocoon composed of 

 small chips of wood and silk. The 

 change to the pupa takes place in 

 May, this stage lasting about fif- 

 teen days. 



Young plants or small twigs are 

 frequently girdled and soon wilt 

 and die. Larger stems are more 

 resistant, but on account of the preference of the insect for places 

 previously attacked, the injury increases from year to year and 

 eventually results in death. Large plants show ugly scars on the 

 trunk and branches. These may be either devoid of bark or loosely 

 covered with dead and perforated pieces. There may also be more 

 or less fine, yellow, granular, not powdery borings thrown out by 

 the caterpillars. The plants are rarely injured within one foot of 

 the ground. 



Fig. 4 Work of rhododendron 



clear-wing borer in stems (natural 

 size, original) 



