L68 



[NJURIOUS AND BENEFICIAL INSECTS <>K CALIFORNIA. 



Life History. — The cactus scale is very prolific and often masses in 

 such numbers as to entirely hide the host. As it usually occurs in 



\v a r ni climates, there are 

 probably several broods a 

 yea)'. 



Nature of Work. — This 

 species w o rks u p o n the 

 joints of cactus, causing con- 

 siderable loss of sap and in 

 not a few cases entirely kill- 

 ing the plant. It is espe- 

 cially troublesome in orna- 

 mental gardens, hothouses 

 and artificial planting's. 



Distribution. — The scale 

 is common throughout the 

 State in hothouses and quite 

 widely distributed out of 

 doors in the central and 

 southern parts. 



Food Plants. -- Various 



species of p u n I i a and 

 Ct rt us arc attacked. 



Control. -- Dipping the 

 I »hints in kerosene or crude 

 oil emulsion before setting 

 out and spraying them with 

 these solutions or ;iiiy of 1 he oil emulsions are recommended. 



Fig. 14-"). — The cactus scale, Diaspis echino- 

 cacti cacti Comst., on Opuntia. Natural size. 

 Collected at Ventura by S. H. Bssig. (Original) 



THE ZAMIA SCALE 



Diaspis samia Morgan 



(Fig. 146) 



Description. — The scales are nearly circular, light gray, with yel- 

 low or dark-brown exuviae near one side. The diameter varies con- 

 siderably but averages about -fa inch. The bodies of the females are 

 yellow. 



Life History. — The life history of this scale is practically the same 

 as for the other species of the same genus. 



Nature of Work. — This is a very prolific species which masses in 

 great numbers upon the leaves and stems of the food plants. Injury 

 is caused by constant sapping of the juices and is manifested by dis- 

 colorations and the unhealthy appearance of the infested plants. 



Distribution. — The zamia scale is commonly taken in quarantine 

 and has become established in greenhouses around San Francisco 

 Hay. 



Food Plants.- Various species of Z<imi<t and the sago palm are 

 attacked. 



