‘thicker at one end, and 
Protection of Mesquite from Borers. 9 
stem, laying eggs along this tunnel; while the larger form lays its 
eggs under scales of bark, as do the roundheaded borers. The grubs 
(figs. 12, 13) which develop from these eggs are curled like a closed 
finger, so that the head 
and the end of the body 
almost meet. They are 
range from one-quarter to 
three-quarters of an inch 
in length. The smaller 
forms appear in enor- 
mous numbers, com- 
pletely riddling the sap- 
wood with cylindrical 
holes tightly packed with fine powder that falls out when disturbed. 
By the time they are full grown they have almost destroyed the sap- 
wood (figs. 4, 14). The grub of the larger form feeds only a short 
while in the sapwood and then goes into the 
heartwood, where most of the feeding is done. 
It seldom attacks freshly cut wood, but shows 
a decided preference for older and drier sticks 
and posts. It has only one generation each 
year. 
The flat-headed borer, as an adult beetle 
(fig. 10), is hard shelled, flattened, oval, from 
one-half to three-quarters of an inch in length, 
and shining bluish black with light golden 
yellow spots on top. It lays 
its eggs on the bark. From 
these develop flattened yel- 
lowish white hammer-shaped 
Fig. 11.—Adult beetle of the medium-sized powder- 
post borer in mesquite. Enlarged. 
eee 
Fig. 12.—Larva, grub, or J F 
boring stage of the Worms (fig. 15), having the 
bao ser most beetle head end of the body much 
in mesquite. Enlarged. ‘ : 
wider than the remainder. 
The larve mine between the bark and wood, grooving 
the sapwood with winding galleries until nearly full 
grown. (Fig. 8.) These mines are flattened in cross 
section and filled with fine, tightly packed “saw- Fi. 18—Larva, 
: : grub, or boring 
dust ” that does not easily fall out, and when it does Eines Ohta ae: 
so loosens in cakes. dium-sized pow- 
> der-post beetle 
in mesquite. En- 
SEASONAL ACTIVITY OF THE BORERS. larged. 
There is practically no month of the year in southern Arizona 
when some few of these beetles do not fly about seeking new wood 
