INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



119 



THE EUROPEAN ELM SCALE 



Gossy i)n rin ul mi (Linnaeus) 



[Goasyparia spuria (Modeer)] 



(Coccus ul mi Linnaeus) 



(Figs. 100, 101) 



Description. — The adult females are readily distinguished by the 

 white cottony fringes around the reddish-brown bodies (Fig. 101). 

 They are from | to nearly f inch long 

 and are usually clustered in the cracks 

 and crevices in great numbers and from 

 a distance appear as white rings. The 

 males are very delicate, reddish, two- 

 winged insects, with two long white 

 anal filaments. The cocoons are white 

 and less than -^ inch long (Fig. 100). 



Life History. 74 — The eggs are oblong 

 in shape, pale yellow, and hatch so 

 quickly that many have thought that 

 the young were born alive. The young 

 appear during the early summer months 

 and settle upon the leaves and smaller 

 twigs until August and September, 

 when they become nearly full-grown. 

 They then move to the twigs and 

 branches for hibernation. The males 

 begin to issue in early spring. 'The 

 females reach maturity and begin to 

 bring forth the summer brood in May 

 and June. There is but one brood a 

 year. 



Nature of Work.— This scale is very 

 prolific and masses in great numbers 

 upon the limbs of the elms. Besides 

 the large amounts of honey-dew sup- 

 porting the smut fungus, which render 

 the trees very unsightly, the attacks 

 greatly lessen their vitality. 



Distribution. — The distribution of the 

 European elm scale is quite definite 

 and apparently confined to the follow- 

 ing localities: San Rafael (Marin County), Ukiah (Mendocino 

 County), Colusa (Colusa County), Palo Alto, Santa Clara, San Jose 

 and Stanford University ( Santa Clara County), Modesto (Stanislaus 

 County) and Stockton (San Joaquin County). 



Food Plants.— The following species of elm trees are attacked by 

 this scale : American elm, cork elm, English elm, slippery elm and 

 Wych or Scotch elm. 



Control. — Washing the insects from the trees with an extension 

 nozzle under high pressure during the period of hatching will control 



74 Doten, S. B., Mo. Bui. Cal. Hort. Com., I, pp. 89-100, 1912. 



Fig. 100. — The European elm 

 scale. Gossyparia ulmi (Linn.). 

 Cocoons of the males in January. 

 Natural size. Taken at Stockton 

 by Wm. Garden. (Original) 



