78 
The Queensland Naturalist. 
April, 1926 
T found the fruits badly attacked by the borer, and a 
week or two afterwards they had "ot into the trunk, 
Avhcre T ])romi)t]y settled them. By this time the cone 
had fallen to pieces, as many cones do (Bunya, casuarina, 
etc.), but not all (e.g., Sequoia: T have some I ^ot in 
California 80 years agfo, still complete). Now these borers 
could only haA'c come from the cyead seeds or from the 
before-mentioned bedstead, which Avas the only' bambu 
article of Eddo's fabrication that entered the house save 
my bedroom chair, and the bedstead was then quite free 
from borers, and only showed CA^idence of their presence 
about the same time as 1 found the pyrethrum dust (T 
suppose someone Avill call this a case of mimicry!) I shall 
j'cturn to tills presently. 
The amount of Avork these borers accomplish is best 
shoAAUi in the follcAA'in^ table: — 
Dust Produced in one day, 27th December, 1924. 
from one chair-back in my bedroom. 
No. of bambu slats in chair 30 1 
Lenji'th of each slat .. .. 20ins, ■ 
Averao'e AA'idth of slats . . 0.75in. ) 
AVei^ht of box and dust 639 grains) 
AVeight of box (a 2oz. - 
Capstan tobacco box) 221 grains! 
AVeight of dust . . . . 418 grains 
AA' eight of dust per sq. 
inch 1.03 grains 
Area gnaAA'ed 
405 sq. in. 
Dust produced 
418 grains 
The AAmy the borers attack the cycad stems is instruc- 
tive. As you know they are encased in an armour of 
old leaf stumps and leaf scales, A'ery hard. Inside this is 
a zone of hard tissue, rejiresenting both ‘bark’ and bast, 
tlien a thin cambium zone. Then comes the real xylem, 
in this case about 4-incb vAude, curious in that the fibro- 
A'ascular tissue is not interlocked into solid woods, but 
j'emains in fairly loose strands like the oakum AA'e play 
with Avhen in jail, but of this more anon. The central 
])ithy iiart of the stem, Avhich constitutes about one-half 
of the Avhole. is of comparatively soft parenchymatous 
tissue traversed by isolated tihrowascular strands. 
The insects bore straight through the armour Avithout 
stopping, save, maybe, to mop their brows, and so 
through the ]ihloem, saA'e a feAc better dentitioned athletes 
who stay and hroAvse, into the pith, in Avhich they r^vpl. 
