No. 5. ] JnsectAcide IVasfies against Date PaLn Scale. 



U3 



INSECTICIDE WASHES AGAINST DATE PALM SCALE.i 



{Reprint of a report published in " Insect Life," Vol. Ill, p. 441, hy 



the United States Entomological Departfnent.] 

 About July 8th, 1890, tlie Department of Agriculture received from 

 Algiers, Africa, nine date-palm trees, two to four feet high after having 

 been cut off at the top, and probably from seven to ten years old from 

 suckers. 



About the 1st of August, fifty-fonr small trees of date palm were re- 

 ceived from CairOj 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. zizi/phi, 

 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 ditficulty experienced in effecting the complete exterminution of 

 the scales by the use of the instctieide 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. 



Tlie 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 16th the plants were still, in many places, 

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

 emulsion diluted ten times. August 18th and 19th 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 No. 22), and two were sprayed with the 

 kerosene emulsion diluted only five times. These trees were examined 

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



' Scale insects attack palms of various kinds in Indin, and tbe following report, there- 

 fore, is interesting as showing the difficulty oC eradiciiting the pest. — Ed. 



