73 



TlIK, WaTHK Si'KAYS 'I'O TI'ST IOki'KCT Oit K'ains. 



In wcUirif^ down tlu; trcres to imit.-ite the ellects of raiti, liltccn 

 {gallons ol water were used to a tret', as a rule, a double .iiiioiint 

 bein^' occasional! y applied as a variation ol the experiment. l''or 

 a tree oi the averaf^c spread ol" tliirteen feet, lilteen {gallons ol 

 water was ecpiivalent to a rainlall ol a sixth ot an inc h, aniountinj^ 

 to a sharp summer shower. 'IMk; wasiiin^^ ami leachinj^" ellec t ol 

 tlie ai)plication was, however, greater than that ol a c.orrespond- 

 inj»" showi-r, sinii- tiii* water spray was not distributed e<)nally over 

 the wiu)le area covt;red by the tr(;e-top, but was made to wet the 

 tree e(jually in all i)arts the middle part ol the tree much mori! 

 freely, C<)nHe«|uently, than the outer parts. It would doubtless be 

 fair to say that the III tt-en-f^allon portion was e<|uivalent in ellect 

 on tlie average i-xperimi-ntal tree to a rainlall ol a third ot an inch, 

 and the doubh- portion, ot course, to twice that amount. 'I'lu; 

 time taken lor the application of (iftcten gallons varied, a<:cor<Iinj4- 

 to th(^ weather and tlie size of tlur tree, froni twenty minutes to 

 thirty or thirty-live;, and for the tliirty-/.Callon api)lication it was never 

 less than an hour. Tlu; water in all cases drii)ped fn-tdy from the 

 trees for some time after si)rayin^ ceased, carryiu}^ with it so 

 much of the insecticickr in solution that the drip was of al)out tlu- 

 color of the original mixture. 



'Vhv a[)i)lications of water were varictd sysli:maticall y as to num- 

 l)(;r, to fre()uency, and to period of tinu- between the insecticide 

 operation and the first f^-eneral wettinj^-. Tree No. 1, for example, 

 was wet every day for a week, commencing the next day after tlu- 

 California wash was ai)i)lied; tree No. 2 was wet but once, and 

 that the day after insecticide treatment; tr(;(; No '. was sjjrayed on 

 the .^d with the (California wash, and with water on the bth and 

 every other day thereafter for three days; trc^; No. (. was si)rayed 

 but once, and then with thirty j^allons of water, one week after in- 

 secticide treatment.; and tree No. '>, the same, (!xcei)t that the wa- 

 ter was applied at the end of two weeks, i'^urther j)articulars may 

 be obtained from the detailed accounts of the ex|)eriments. 



JVXIM.ANA'IION ()!■ TaHLKS. 



Tlie four tables in the text have been [)repared to present in 

 summary form the detailed results of the treatment for each tree 

 as shown by successive counts of scales on selected samjjle twij;fs 

 and branches. Against the number of each tree is i)laced for each 

 date on which special observations were made, the number of 

 scales counted and the percentaj^'e of scales killed by the inse( ticide 

 up to that time. Tlu; lirst count shows always tlu; jjcrcentag-c of 



