108 INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 



were used in combatting them, but during the past few years fumi- 

 gation, especially in the citrus growing sections of the State, has 

 become the principal control method. Scale insects occurring on 

 deciduous fruit trees are most efficiently and cheaply controlled by 

 the use of sprays, and the mealy bugs on citrus and other trees are 

 also usually subjected to a similar treatment. All armored scales 

 (red scale, yellow scale, purple scale, etc.), as well as such unarmored 

 scales as the black scale and soft brown scale on citrus trees, are most 

 i ffectively controlled by fumigation. 



Natural Enemies.— One of the most noted examples of the control 

 of a serious insect pest by natural enemies is that of the cottony 

 cushion scale (Icerya purchasi) by the Vedalia (Nouius cardinalis). 

 Other ladybird beetles and internal parasites also form an important 

 pari in the control of scale insects, being apparently responsible for 

 the subjection of many non-economic species. Other insects, also, 

 prey upon coccids, as will be noted in the discussion of the various 

 species. 



Subfamilies.— In this work only five of the many subfamilies will 

 be considered, as these embrace all of the common species known in 

 California. They are : 

 Monophlebince 

 Ortheziina 

 Dactylopiina 



Cocci an 

 Diaspince 



MONOPHLEBIN^ (Subfamily) 



The females belonging to this subfamily are characterized by 

 secreting, behind the soft and unprotected bodies, a large white cot- 

 tony egg-sac. The bodies of the young scales are almost entirely 

 without protective covering, while those of the adult females are 

 usually covered with a waxy secretion. The males are delicate, two- 

 Avinged insects. In California we have but one species, the cottony 

 cushion or fluted scale (Icerya purchasi), which is of economic im- 

 portance. 



THE COTTONY CUSHION OR FLUTED SCALE 

 Icerya purchasi Maskell 68 



(Fig. SS) 



Description.— The fully-matured females are easily distinguished by 

 the large, white, fluted, cottony egg masses at the posterior end of 

 the red, yellow or dark brown bodies — which together are from \ to \ 

 inch long and three fourths as wide. The eggs are deposited within 

 the cottony mass and are oblong and rich cardinal-red. From four 

 hundred to a thousand may be laid by a single female. The young 

 are bright red with dusky legs and antennae and several long tail- 



« 8 Two varieties of Icerya purchasi have been named by Dr. T. D. A. Cockerell as 

 follows: crawii in which the body proper is yellow or light brown and maslcelli in 

 Which the body is dark brown or almost black. The two varieties are undoubtedly 

 ;i single species with slight differences in color which vary from yellow to almost 

 black with all shades between. 



