240 POLYGRAPHUS MINOR, US. 

It is probable that this insect has three to four generations 
in the year in favourable seasons, the first flight of beetles, from 
the eggs laid at the beginning of May or late in April, appearing 
towards the end of May ([ have found pupz ‘and lightish brown 
immature beetles in the galleries. on the 22nd May). These at 
once lay eggs and a second generation of beetles appears about 
the beginning of July. Immature beetles were found on 22nd 
June at about the same elevation as those found on 22nd May. 
A third brood of beetles from eggs laid by these latter makes 
its appearance at the end of September and beginning of 
October and at once layseggs. These latter develop into larve, 
a portion of which may reach the beetle stage and hibernate as 
such through the winter. It would appear, however, that a large 
number pass the cold weather as larvae enveloped in a thin, 
white, papery cocoon at the end of their larval galleries which 
they slightly enlarge. Early in April these probably turn into 
pup, the resulting beetles emerging from the tree towards the 
end of the month. 
The number of generations and time spent in each 
require further study and corroboration. 
The ¢ bores into the bast through the bark of the tree 
and excavates in it a pairing chamber, being joined there 
by the @. At present my observations have shown me that 
there are always two beetles to be found in this chamber 
whilst it is under construction. After pairing has taken place, 
the @ bores an egg gallery away from the chamber in the bast 
and lays her eggs in this. In Pl. XIII, fig, 1, d, the small 
chamber, p', containing a beetle is the pairing chamber from 
which an egg gallery is just being started. The usual number 
of egg galleries bored away from the pairing chamber appears 
to be five (see Pl. XV, figs. 2, 3, 4, ~. ¢.). It often happens that 
in leaving the pairing chamber the @ bores the egg gallery for 
some distance in the thick bast layer without breaking through 
the inner surface. In such cases the number of ege galleries 
bored away from the pairing chamber appear to be smaller than 
they really are. The larval galleries are situated entirely inthe 
bast and take off approximately at right angles but curve away 
later on (see PI. XV, figs. 2, 3, 4,1.). The sapwood is not touched 
