6 BULLETIN 184, U. S. DEPARTMENT OF AGRICULTURE. 
observed to the last three when there was sufficient huisache in close 
proximity to the emerging beetles. In fact, the greatest amount of 
damage to " huajilla " and " ratama " was noticed when collections 
of huisache branches containing larvae were left near ratama and 
huajilla trees. 
LIFE HISTORY. 
The beetles begin to appear early in September and continue to 
emerge from their pupal cavities until the latter part of November, 
though most of the brood issues during the month of October. In 
the laboratory most of the material encaged developed adult beetles by 
October 12. The adults remain for several days in their pupal cells 
after they have emerged from the pupal cases before attempting to cut 
their way out of the pupal cavities through the bark of the branch. 
Just as soon as they have partaken of a little food, which consists 
of bark from the branch, and the wing covers are sufficiently hard- 
ened, copulation begins. Of specimens observed in the laboratory 
none began copulating or showed activity before two days after 
their emergence in the adult stage. This species of Oncideres, un- 
like its near relatives, Oncideres cingulata and 0. teccana, does not 
so frequently work in pairs. The writer has found the beetles work- 
ing in pairs, but during midseason they occur to a greater or less 
extent in colonies. The writer has observed as many as 24 on one 
small tree, and two-thirds of them at times would be females. The 
males go from one female to another, and do not seem to possess the 
monogamous instinct. 
While making observations on the species during October, 1910, 
it was decided to see how long a period was required for one unas- 
sisted female to prepare the egg cavity and deposit an egg. The first 
one tried deposited in 1 minute and 35 seconds, another in 4 minutes 
and 50 seconds, and the next in 4 minutes and 40 seconds. Observa- 
tions made later show that from 1 to 5 minutes is ordinarily required 
for the female beetle to deposit. This, however, does not include pre- 
paring the cavity to receive the egg, for it generally requires about 10 
minutes to prepare the cavity. The beetle begins this cavity by insert- 
ing both mandibles as deeply as possible into the bark of the branch 
that is to be girdled. After forcing the mandibles deep into the 
bark the beetle draws them together as nearly as she can. Then one 
is removed and the other worked deeply into the puncture. It is 
then removed and the other mandible is inserted in the same manner. 
Later both mandibles are inserted and a tiny chip removed. Then 
the work begins again with one mandible at a time, until the 
cavity is prepared to receive the egg. The beetle then reverses its 
position and forces the ovipositor into the cavity as deeply as pos- 
sible. Shortly the egg can be seen leaving the body of the beetle. 
After the egg is inserted the beetle frees herself by withdrawing the 
