INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 75 



The life history has not been worked out in California. In the spring 

 of the year and during the summer females have been found on the 

 Douglas spruce, but the gall-producing form has not been observed. 



Nature of Work. — Though trees are never killed by the attacks 

 of the lice, they often appear stunted and very unsightly because of the 

 large amount of honey-dew over which the black fungus grows. Char- 

 acteristic terminal galls are also formed on the twigs of the silver spruce, 

 as stated above. 



Distribution. — The Chermes are not at all common in this State. 

 This species is most often met with and occurs throughout the central 

 and northern parts of the State, principally in parks and gardens. It is 

 quite abundant in the San Francisco Bay region, especially in San 

 Francisco, San Mateo and Santa Clara counties. 



Food Plants.— Professor Gillette records the following hosts in 

 Colorado: The red fir (Abies magnified), Douglas spruce and silver 

 spruce (Picea parry ana) . W. M. Davidson has taken it on the false 

 spruce (Pseudotsuya douglasii) at Stanford University. 48 The writer 

 has collected it on the Douglas spruce in the Golden Gate Park, San 

 Francisco, where it has also been repeatedly taken by Mr. Harold 

 Compere. 



Control.— The best control measures consist in the application of 

 miscible oil, crude oil emulsion or carbolic acid emulsion sprays dur- 

 ing the winter months when the insects are in an immature condition 

 and lack the waxy covering. 



THE BEET ROOT APHIS 



Pemphigus betce Doane 



Description.— The adult wingless aphis is about ^ inch long, some- 

 what rounded or elongated in shape, whitish or pale yellow in color, 

 with a large tuft of white flocculence covering the tip of the abdomen. 

 The legs, antenna? and spots on the top of the head are brown. The 

 winged louse is a little larger, more elongated and much darker in 

 color. The head, antennae, legs and thorax are black and are usually 

 covered with a fine, white powder, appearing bluish-black. The abdo- 

 men is dark green. The presence of this pest is easily told by the white 

 flocculence which covers the bodies. 



Life History.— Most of the wingless, viviparous females feed upon 

 the tubers of beets and roots of weeds and other plants during the 

 summer. In the fall, winged migrants fly to cottonwood trees and 

 give birth to true sexual males and females, which mate and each 

 female deposits a single winter eixg in the crevice of the bark, which 

 does not hatch until the following spring. The young lice hatching 

 from these eggs, about the time the leaves appear in the spring, are 

 known as stem-mothers. They settle upon the leaves and according 

 to Professor Gillette do not produce a gall but fold the leaves in 

 which the first generation of young are reared. The migrants from 

 the cottonwoods fly to the fields and infest beets and other plants 

 and give rise to the summer apterous and winged forms, some of the 



"Jr. Ec. Ent., Ill, p. 372, 1910. 



