EXPERIMENTS WITH SPR^ SOLUTINS* JSpR, SREEN LOGS. 5 



materials recommended by va'fio'us* correspondents or suggested by 

 the forest insect personnel. Dr. J. K. Haywood, chairman of the 

 Insecticide and Fungicide Board, United States Department of 

 Agriculture, also gave some very interesting suggestions. 



These experiments are to be considered as only of a preliminary 

 character. The objects were chiefly to determine the requisites of 

 an effective spray and to study the behavior of the different types 

 of insects in relation to various treatments and methods of applica- 

 tion, as well as to find an effective spray. 



The solutions were tried principally on two kinds of wood pine 

 and ash although occasionally hickory, juniper, and oak were used. 

 The wood was cut at a time to give the most favorable condition 

 for insect attack hickory and juniper about January 1, pine and 

 ash about March 15. It was treated immediately or held in a wire 

 insectary until treated. The individual pieces of wood used were 

 3 feet long and averaged from 6 to 10 inches in diameter. 



Insects of all types were represented in the tests. The following 

 were the most abundant and economically the most important: 

 Neoclytus erythrocephalus Fab. on ash and hickory, Xylotrechus 

 colonus Fab. on oak and hickory, Aserrwm moestimi Hald. on pine, 

 Cyllene pictus Drury on hickory, and Hylotrupes ligneus Fab. on 

 juniper all of type 1 ; M onohammus scutellatus Say and M. titillator 

 Fab. on pine both of type 2 (no species of type 2 on other woods) ; 

 various species of Ips, Phloeosinus, and Hylesinus on pine, juniper, 

 and ash, respectively of type 4; various species of ambrosia beetles 

 on pine and oak of type 3. 



From the foregoing it is seen that pine was tested against all four 

 types; ash against types 1, 3, and 4; hickory against type 1; juniper 

 against types 1 and 4 ; and oak against types 1 and 3. Owing to the 

 seasonal variations in the abundance of the various species of insects 

 the tests were not conclusive every season. For example, in 1918 and 

 1919 Monohammus was very abundant and attacked all the controls 

 as well as many treated woods, while in 1920 very few were present 

 and not all control logs were attacked. Again, in 1918 Hylesinus 

 (type 4) in ash was abundant, though in 1920 very few of the con- 

 trol logs were attacked. Every year, however, some one type was very 

 abundant on all species of wood used. 



The flight period of these insects has a certain bearing on the re- 

 sults, as those species flying late in the season found the logs after 

 they were exposed to weathering for a month or more. Most of the 

 treatments were made about April 1, or 15 days before the flight of the 

 first insects, and unless otherwise stated this time of treatment is to 

 be inferred. With certain materials treatments were made also on 

 June 1 at the time of the first flight of some other species. The flight 

 periods are given in Table I. 

 10223022 2 



