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REPORT ON CALIFORNIA INSECTS. 
3y ALBERT KOEBELE, Special Agent. 
LETTER OF TRANSMITTAL. 
ALAMEDA, CAL. October 25, 1889. 
Sir: I herewith submit my report upon observations made and work done since 
my return from Australia. 
After returning to Alameda on April 15, some time was taken up in writing out 
my reports upon work done in Australia, and also in assisting in raising and distrib- 
uting in the northern part of this State the Australian Ladybird-enemy of the Icerya. 
This Ladybird does remarkably good and speedy work everywhere. As usual my chief 
work has been the breeding and studying of all insects, injurious and otherwise, that 
have come under my notice, the special notes on which will accompany material that 
will be sent in. 
Respectfully, 
ALBERT KOEBELE. 
Prose Vi RILEY, 
U.S. Entomologist. 
THE MADRONA TREE BORER. 
(Polycaon confertus Lec.) 
This destructive beetle occurs toa greater or less extent every spring 
and summer upon various fruit-trees, vines, ete., boring into the fresh 
wood and destroying it. During my stay in the Santa Cruz Mountains 
the past summer they were observed everywhere, and most abundantly 
during May and June. On any dead tree, as soon as the leaves begin 
to fade, this beetle may be found, though always most abundantly upon 
the Madrona tree (Arbutus menziesii). Old trees of this species, such as 
have been allowed to lay on the ground for a year or two, are always 
completely perforated with holes from which these beetles have made 
their exit. In cutting through, one finds the wood nothing but mines 
produced by the larve, the mines generally running lengthwise, but often 
crossing each other. The Madrona tree seems to be the ordinary if not 
the only plant in which the beetle breeds. Notwithstanding that the 
mature insect bores in almost any kind of fresh wood, and especially 
favors such as has been somewhat injured by the hot sun, the larva is 
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