344 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 14 



The pest is controlled by spraying with the regular oil emulsion sprays. 

 Two sprayings generally are necessary, one during the spring at a 

 strength of 1 to 80 and another in the fall at 1 to 70. 



A question of considerable importance arises in connection with 

 spraying with oil emulsions in southern Florida. The waters which 

 are generally used for spraying purposes come from wells situated in 

 limestone formation and are termed "hard". They generally contain 

 bi-carbonate salts and when combined with oil emulsion sprays at 

 times separation occurs, with the result that free oil is produced which 

 is detrimental to avocado foliage. Softening of the water is necessary 

 when using an oil emulsion which otherwise separates when combined 

 with such water. Recently the oil emulsions are being perfected by 

 the incorporation of organic stabilizers in their manufacture which pre- 

 vents separation to a marked degree. 



At times various scale insects give the avojado grower considerable 

 trouble. One in particular is the Dictyospermum scale (Chrysompha- 

 lus dictyospermum Morgan), which makes inroads into the tree, attack- 

 ing the twigs, branches and where numerous, the foliage. Its ef 

 feet on the avocado is very similar to that produced by the San Jose 

 scale on various deciduous fruits. 



Another scale which seriouply attacks the avocado is the Pyriform 

 scale {Protopulvinaria pyriformis Ckll.). This scale attacks the young 

 foliage in the spring, the immature scales migrating as they hatch from 

 the matirre scales on the older foliage. In the process of development 

 of this scale honeydew is produced in practically the same manner as 

 when white flies are present, eventually giving the fruit and tree a 

 decided dirty blackened appearance. The Dictyospermiim scale and 

 the P3^rifomi scale are controlled by spraying with oil emulsion sprays 

 during the dormant season of the year at a strength of 1 to 70. 



Various other insects which attack the avocado may cause serious 

 damage at times are: the blossom anomala (Anomala undulata Mels.); 

 the avocado tingid {Acysta perseae Heid.); the avocado leaf hopper 

 {Empoasca minuenda Ball); the cocoanut mealy bug, {Pseudococcus 

 nipae Mask.) ; the black scale {Saissetia oleae Ber.) ; the avocado leaf 

 roller (Gracilaria perseael^nscV:); and the cotton stainer (Dvsdercus 

 SMturellus H. Schf.). 



