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JOURNAL 
OF 
ECONOMIC ENTOMOLOGY 
OFFICIAL ORGAN AMERICAN ASSOCIATION OF ECONOMIC ENTOMOLOGISTS 
Vol. 13 OCTOBER, 1920 No. 4 
Proceedings of the Thirty-Second Annual Meeting of the 
American Association of Economic Entomologists 
(Continued from p. 363 ) 
PAPERS READ BY TITLE 
THE PACIFIC OAK TWIG-GIRDLER 1 
By H. E. Burke, Specialist in Forest Entomology , Forest Insect Investigations , 
Bureau of Entomology , U. S. Department of Agriculture 
Economic Importance 
One of the most important and characteristic native shade trees of 
the coast valleys of California is the California live oak (Quercus 
agrifolia Nee). As a general rule this fine tree is in a healthy and 
vigorous condition, but sometimes it is attacked by various insects, 
which give it a ragged and unsightly appearance. One of the most 
important of these insects is the twig-girdler. Both small and large 
trees sometimes are thickly spotted with small areas of fading, yel¬ 
low, red or brownish foliage which stands out strikingly against the 
normal green of the healthy leaves. In the majority of cases the dead 
twig or small branch bearing the coloring leaves will show at its base 
the characteristic spirally-winding mine of the twig-girdler. Some¬ 
times so many twigs and small branches are killed by the girdler that 
the tree dies. In any case, the ragged appearance caused by numbers 
of dead and dying twigs seriously injures the tree for ornamental 
purposes. 
History and Identity 
The species was described by Dr. George H. Horn in 1891, with host 
plant unknown. (Trans. Amer. Ent. Soc., Vol. XVIII, p. 298.) 
1 Agrilus angelius Horn, family Buprestidae, order Coleoptera. 
