22 SCALE -INSECTS 



undoubtedly equally as good as the last, and costs one cent less per 

 gallon. 



No. 8. Solid concentrated American lye (80 per cent.) . . 1 lb., or 

 any one of the sodas in preceding formula, to 



Commercial potash (52 per cent. ) i lb. 



Water 2 gals. 



Simply dissolve. This is just a little more than one half the 

 strength of potash that is given in the preceding formula. 



Comments. The above 8 washes are given so as to allow some 

 latitude in choice. They have been carefully selected, and will 

 doubtless all prove more or less efficient. Those which will be of 

 use for species of Aspidiotus and L&canium, are mentioned above. 

 The last two formulas mentioned would, I believe, be especially ad- 

 apted to our climate. 



For Lecanodiaspis, or other scales on Dasylirion and Yucca, I 

 would recommend formula No. 6, to be applied at any time of the 

 year. No. 4 diluted five times would also be of service, and would 

 in all probability not affect the plants. 



As far as the scale on Larrea goes, it will probably not spread 

 to any other plant, and doubtless the creosote bush is not valuable 

 enough here to call for any protection. However, No. P> and No. 4, 

 as above recommended, would be the proper remedies. 



For species of Icerya, and for cottony scale on mesquite, No. 3 is 

 the formula which should be used, but the caution given above as to 

 trying the wash first to get the strength which will not injure such 

 foliage as grape or mesquite, must be heeded. 



No mention is made in this bulletin of the hydrocyanic acid 

 gas method of destroying scale-insects, which is at the present time 

 unnecessary in this territory. 



EXPLANATION OF PLATES. 



Plate I. 



( All much enlarged. ) 



Fig. 1. San Jose scale, Aspidiotus pprniciosits. last abdominal segment of female 

 showing specific characters. 



