1-ltOCEEDIXGS or THE THIEU ENTOMOLOCilCAL MEETING 873 



is very active, its movements causing a sort of wave to travel along the 

 frass covering the burrow. Larvae have no power of swinging by silk 

 threads if they fall out of the burrow. 



Pupa. 

 The pre-pupal larva is yellow, and active if disturbed. It is some 

 considerable time, up to a month, in this stage before finally pupating, 

 during which time it is mostly found in the pupal pit, but not always. 

 This pupal pit is an oval depression eaten below the bottom of the burrow 

 to a depth of 2 to 3 mm., the bottom of the pit being thus about 5 mm. 

 from the outer surface of the bark, and very close to the lactiferous layer. 

 The pvTpal pit is about 1.5 mm. by 5 mm. along the major and 

 minor axes. The pupa lies free within with the last larval skin free 

 behind it. The pit is ceiled by a stiff brown silk membrane tightly 

 stretched across it be'ow the main webbing of the burrow, which is 

 usually considerably elevated at this point, making the location of the 

 pupa easy. On younger trees (up to ten years old or so), where they are 

 often still visible, pupation frequently occurs in the branch scars, possibly 

 because, except at these points, the lactiferous layer is too near the sur- 

 face to permit of the excavation of the pupal pit. Pupae in these scars 

 are more difficult of discovery aS the outer webbing is not always so 

 noticeably raised above them. 



The pupa itself is 7 mm. long (male) to 9 mm. long (female) : ochreous, 

 incompletely obtect, the wing cases somewhat free above. In the labo- 

 ratory emergence usually occurs during the afternoon. 



Life-History. 



I have not found larvre before January, at which time they are obvi- 

 ously quite young. Their growth is slow, and they mature and pupate 

 from the third week in July onwards for about a month, being earliest 

 (as far as this estate is concerned) in an area near the Southern boimdary 

 where the infestation is annually heavy, and latest on an outlying divi- 

 sion two miles to the North where so far it has been slight. The middle 

 of September .sees the last imagines out. Pupal period 26 days. 



I have never taken imagines Save in August and September, and I 

 have not found any hibernating pupae. It is unlikely that so, delicate 

 a moth in large areas of pure robber which afford no shelter can remain 

 alive until December for oviposition, which makes the non-discovery of 

 the egg the more remarkable, as it must be in this stage that the insect 

 spends the four intervening months till January. 



