FAMILY CEKAMBYCIDAE 315 



of another portion of the bark will disclose masses of it m situ in the 

 galleries ; from one portion of the gallery a hole will be seen proceeding 

 down into the wood, and if this is traced downwards the empty pupal 

 chamber will be found. 



(b) Trees Less Badly Attacked, but which imll Eventually Die under the 

 Attacks. — Holes and small rotting areas on the bark, often at the junction 

 ot branches with the main stem, are visible, and, below these, exudations 

 of sap, either fresh and trickling or dried to the bark beneath the hole. 

 These exudations are usually in large irregular masses, tailing off below 

 into thin trickles, the sap having dried on its way down the stem. PI. vii 

 shows a heavy outflow of sap down a poplar-tree. If some of these holes 

 with the fresh exudations trickling from them are cut into towards the 

 end of May and commencement of June and examined carefully, they 

 will be found to contain one or more little clusters of eggs placed on the 

 edges of the bark and well down in the sappy inner portion of it ; later on 

 in June numerous young larvae may be found here. If examined later in 

 the summer, the careful paring away of the bark will disclose the grub in 

 its half-formed gallery which grooves both the inner bark and sapwood. If 

 holes on which the exudation has dried but is still fresh are cut into, they 

 will show (provided they are not merely the old exit-holes of the beetle, 

 when they may or may not disclose other insects, depending upon whether 

 female beetles took advantage of them to lay eggs in) one of the following 

 stages: if cut into in the autumn, the grub will be found nearly three- 

 quarters or more grown, having nearly completed its sapwood gallery ; 

 later on in the winter the grub will be found to be boring its tunnel down 

 into the wood, or quiescent, hibernating for a part of this period ; late in 

 May it will be necessary to cut right down into the wood, when the grub 

 will be found in the interior in, or making, its pupal chamber. 



If the exudation below the holes is dry and old-looking, an examination 

 of them will disclose in the autumn the pupae in the pupal chamber in the 

 interior of the wood, in the winter about January or February the fully 

 formed but still soft beetle in the same position, and about the beginning of 

 April the fully formed beetle commencing to make or engaged in making its 

 way through the layer of wood and bark or up the larval tunnel, or no insect at 

 all, but merely this exit-tunnel, if the galleries are more than two }'ears old. 



(c) Trees but Slightly Attacked. — These may show only one or two holes 

 or patches of sap exudation, but according to the appearance of the latter 

 and the time of the year it will be quite possible to form an accurate estimate 

 of the stage arrived at by the insect in them. 



The life history shows that the beetle seeks out wounds on the trees it 



affects in which to lay its eggs. It follows, therefore, 



j> ,. that all wounds made in trees at the egg-laying period 



are so many facilities to the beetle in her egg-laying 



operations. Since she lays her fifty eggs in clusters of about ten, failing 



wounds in the trees she has to bore out small areas herself m which to 



