442 



About the 1st of August, fifty-four small trees of Date Palm were re- 

 ceived from Cairo, Egypt, one to two feet high and about three years 

 old from suckers. These trees were all badly infested with a species of 

 Parlatoria which proved, on comparison, to be identical with P. zizyphi 

 Lucas. As it was the intention of the Department to establish these trees 

 in California, and it was highly undesirable to introduce the scale with 

 them, the entomologist was instructed to take steps to destroy the insects 

 and free the plants. The efforts to do so are of interest in view of the 

 great difficulty experienced in effecting the complete extermination of 

 the scales by the use of the insecticide washes which our experience 

 has shown to be so successful against the various introduced and native 

 scale-insects of our orchards. 



The difficulty was in part due to some peculiarity of the scales them- 

 selves, and also to the fact that they were so thickly massed that the 

 underlying insects were at first not reached by the insecticides. It em- 

 phasizes the necessity of abundant caution in all similar cases and the 

 need of the most thorough and intelligent supervision. 



The first lot of trees were sprayed about the middle of July and the 

 second lot about the 1st of August with kerosene and soap emulsion 

 diluted fifteen times. August 16 the plants were still, in many places 

 covered with live scales and were all again sprayed with the kerosene 

 emulsion diluted ten times. August 18 and 19 examination showed a 

 considerable percentage of seemingly healthy scales. The trees were 

 uninjured. Two test sprayings were then made as follows: Two of the 

 younger lot of trees were sprayed with the resin wash made after Co- 

 quillett's formula (see Bulletin JTo. 22), and two were sprayed with the 

 kerosene emulsion diluted only five times. These trees were examined 

 August 22 and September 2, and the effect of these applications noted 

 as follows : The resin treatment was practically without value and had 

 no injurious eifect on the plants ; the trees treated with the kerosene 

 were, August 22, somewhat yellowed and injured and the scales were 

 all apparently dead. Later, September 2, the plants had partly re- 

 gained their normal color and no living scales were found. 



On September 5 all the trees w^re carefully examined, and about 5 

 per cent of living scales were found, showing that many of the scales 

 at first apparently unaffected by the earlier washings had eventually 

 succumbed. 



It was hoped that the remaining living scales had been affected and 

 would die, but examination, September 18, showed about the same 

 percentage of healthy scales and also a few young. The trees were 

 then thoroughly washed with a stiff brush to remove the loosely adher- 

 ing dead scales and were again sprayed October 4, with a newly made 

 and excellent kerosene and soap emulsion diluted eight times. Contin- 

 uous rains fell on the 6th and 7th, and on October 8 very few living 

 and apparently healthy scales weje found. October 9 the application 



