INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



151 



Food Plants.— Apple, apricot, mountain ash, birch, cherry, elm, 

 grape, hawthorn, laurel, loganberry, orange, peach, pear, plum, prune, 

 rose, sycamore and English walnut are attacked. 



Control. — Control measures are the same as for the European fruit 

 Lecanium (Lecanium corni Bouche). It is seldom necessary to employ 

 such measures for this scale, as it ^_ 

 rarely proves a pest. 



Natural Enemies. — Natural 

 enemies must be responsible for 

 the holding in check of this scale, 

 as no other factors appear to 

 enter into its not becoming more 

 abundant and harmful. The 

 larva? of ladybird beetles and of 

 the green laeewing (Chrysopa 

 calif ornica) feed upon the young. 

 The internal l^menopterous 

 parasite (Corny s fusca) is by far 

 the most effective enemy. 



THE HEMISPHERICAL SCALE 



Saissetia hemisplmrica (Targ.) 



(Lecanium hentisphwricum Targ.) 



(Fig. 130) 



Description. — The adults are 

 regularly oval or hemispherical in 

 shape and slightly over -| inch in 

 diameter. The surface is polished 

 and shining and the color light 

 or dark brown without markings. 

 The eggs are very small and vary from pearly-white to cream color. 



Life History. — The eggs are usually laid during the months of May, 

 June and July and begin to hatch soon after they are laid, thus the 

 single brood is quite uneven, stretching over a period of nearly three 

 months. The young scales settle upon the leaves and smaller branches 

 and do not reach maturity until the following spring or early summer, 

 when egg-laying commences. Though often very abundant upon indi- 

 vidual plants it has not become a serious pest outside of the green- 

 houses, where it does sometimes prove to be a nuisance. 



Nature of Work.— The young and adults work upon the leaves and 

 branches of the host, often occurring in sufficient numbers to entirely 

 hide the bark. On orange trees the adults are often found around 

 the edges of the leaves, as well as upon the smaller branches. It also 

 occurs sparingly upon the fruit. 



Distribution. — The hemispherical scale is a general greenhouse pest 

 throughout the State. In southern California it is quite common, espe- 

 cially in parks and ornamental gardens. 



Food Plants. — Aloe, asparagus ferns, Bignonia, camellia, chrysan- 

 themum, citron, croton, ferns, grapefruit, guava, mountain holly, 



Fig. 129. — The oak Lecanium. Lecanium 

 quercitronis Fitch, on valley oak. En- 

 larged twice. (Original) 



