BTLLETIN 1223, U. S. DEPARTMENT OF AGRICULTURE. 



of Salt Lake City and in the region between these two extremes, 

 where it occasionally does severe damage. In Nevada it is confined 

 to a limited area in the west-central part of the State, extending 

 from Carson City to Eeno, according to S. B. Doten (3, -5), director 

 of the Nevada Agricultural Experiment Station, and from the 

 writer's personal observations. A. L. Melander (16). entomologist 

 of the Washington Agricultural Experiment Station, reports that 

 he has not found it anywhere in the State of Washington, except 

 at Spokane, where it has been for 15 years or more. The files of 

 the Bureau of Entomology also contain records of this insect oc- 

 curring at Coeur d' Alene and Boise, Idaho. 



In California, the insect is somewhat more widespread, occuring 

 in a number of localities in the northern and central portions of 

 the State. It has been found in or near the following towns : Ukiah, 



San Rafael, Colusa, 

 Woodland, Davis, 

 Sacramento, Stock- 

 ton, Modesto, Oak- 

 dale, W o o d s i d e , 

 Redwood City, Palo 

 Alto, Stanford Uni- 

 versity, May field, 

 Mountain View, Los 

 Altos, Santa Clara, 

 College Park, San 

 Jose, Milpitas, Eden- 

 vale, Los Gatos, and 

 Saratoga. 



Additional locali- 

 ties in the United 

 States and Canada 

 have been recorded 

 bv Albert Hart- 

 zell(S). 



SPREAD. 



Fig. 1. — Known distribution of European elm scale in the 

 West. 



The elm scale was 

 in all probability 

 brought to America 

 from Europe on J^oung elm trees. The shipment of elm stock from 

 infested nurseries to various parts of the United States has also been 

 the cause of its being scattered over such a wide territory. 



In these infested localities the scale has spread from tree to tree 

 by several agencies. Birds, such as English sparrows, which are 

 to be found in large numbers in the shade trees of almost any town, 

 probably carry the young crawling scales for considerable distances 

 on their feet. During the fall infested leaves drop to the ground 

 and are blown for some distance by the wind. A certain percentage 

 of these larva? happen to find themselves at the base of an elm tree 

 and crawl up to start a new infestation. The European elm scale 

 has been seen spreading in this manner by both Professor Doten 

 and the AYriter. The Argentine (Iridomyrmex humilis Mayr) and 



