250 STATE BOARD OF HORTICULTURE. 



Genus LECANIUM, Illiger. 



Females naked, flat or convex, viviparous or oviparous, 

 propagating without ovisac, arboreal. 



The following species have been discovered in this State: 



(1) Black scale — Lecanium olex, Bernard. 



(2) Soft scale — Lecanium hesperidiim, Linnteus. 



(3) Hemispherical scale — Lecaniit7nhemisphiericum,Tsirgioni. 



(1) Black Scale. 



(Fig. 6, Plate XXVI.) 



A blackish-brown scale, very common throughout the State. 

 Infests nearly every kind of tree and plant. It is more 

 troublesome on the olive, next to which citrus trees sufi'er the 

 most from its attacks. 



Adult female dark brown, nearly black, nearly hemispherical 

 in form, often quite as long as broad; average length, 4 mm. 

 to 5 mm.; average height, 3 mm. Eggs long, oval, 0.4 mm. in 

 length, color yellowish. Larva flat and six-iointed. 



Undoubtedly European, and infests a greater variety of 

 plants than any other insect of this group. There are several 

 parasites that attack it, and with the aid of predaceous ones, 

 especially the Rhizohius vcntralis, recently introduced, it is 

 kept in check in some localities to a considerable extent. It 

 is most troublesome in the coast and bay regions. As this 

 scale has but one brood a year, which is hatched during the 

 summer, it is greatly reduced in number by the heat in the 

 interior regions. 



Treatment. — Rosin solution (formula No. 2), kerosene emul- 

 sion (formula No. 3), and gas treatment (formula No. 4). On 

 all trees which do not shed their leaves the gas treatment is 

 the only remedy found to efficiently destroy this scale. When 

 properljf applied it should destroy over 99 per cent. The 

 washes and sprays are with difficulty made to reach over 80 

 or 90 per cent of the tree area. The remaining live scale soon 

 reestablish themselves. 



(2) Soft Scale. 



A dark brown, oval scale, infesting citrus trees and orna- 

 mental plants. 



