112 PROTECTION OF PLANTS — 1923-24 



sor, showing much irritation, at the same time emitting in considerable quan- 

 tities a dark-coloured liquid of a strong pungent, acetic acid odour. With 

 the ability to move backward quite as readily and swiftly as forward, at the 

 slightest warning of danger it will beat a hasty retreat to the further end of 

 its burrow and remain there motionless. The larva also can reverse its posi- 

 tion in the tunnel, if necessary, the largest being able to turn easily within the 

 narrowest confines of its burrow. 



Light. 



The action of light has a marked effect on both adults and larvae. While 

 the moths would mate and oviposit in the sunshine, they showed an aversion 

 to bright artificial light. Several females confined for egg records at the field 

 laboratory alwaj^s become much agitated when a light was flashed upon them 

 at night; where previously they were resting quietly, at the approach of the 

 light their wings trembled, antennae and legs moved nervously and a general 

 unrest was exhibited. On removing the light they settled down again. 



The very young larvae if in any way exposed to daylight would make e /ery 

 effort to seek cover, persistently shunning the open and hiding beneath their 

 empty shells or any other covering available; in fact the silk webbing always 

 in evidence, was used to form a covering under which the larvae endeavoured 

 to keep themselves sheltered. 



Temperature. 



Larval activities are influenced by temperature. Certain trees known to 

 have borers working in them were marked in the autumn. The following 

 spring work began before the leaves appeared, and provided the temperature 

 remained about SO^-F, the frass would be expelled freely; but if there occurred a 

 drop of 15 or 20 degrees, as frequently happens in late spring, no sign of 

 their work would be found. However, on the rise again of the mercury the 

 boring dust would appear. This response was not immediate, but rather a 

 -gradual one. 



It was also noticed that the largest number of borings appeared on the 

 warmer sides of the trees, viz; the southeastern, south, and southwestern sides. 

 Isolated oaks, and those more or less in a protected situation, or so located as 

 to receive the sun's rays upon their trunks and branches for the greater part of 

 the day, appeared to be special objects for egg deposition and larval attack. 



These preferences would seem to indicate considerable response to thermo- 

 tropic stimulation by the moth at oviposition and the larvae during boring 

 operations. 



Locomotion. 



Some simple experiments were tried to determine what effect the surface 

 character of several objects would have on the movement of the moth. It 

 was found that on very smooth material like glass, tin, and polished wood 

 the moth could not walk, even when these were placed horizontally, the legs 

 would be vigoroash^ used but with no result. On paper and on very smooth 

 wood movements were very slow; on coarse or roughened bark progress 

 was noimal. 



