April, 1935 J Agricultural Research in N. H. 17 



mine oleate. Nine species of plant leaves and seven of plant stems were 

 used as surfaces. Paraffin-coated glass slides and two species of insects were 

 used for comparison. Surface tensions were measured. 



The results of the investigation are now being prepared for publication. 



A further line of investigation now begun is concerned with the influence 

 of temperature, moisture, and sunlight on the contact performance of a given 

 spray material. In addition, preliminary studies indicate that at least some 

 materials exhibit different contact qualities when delivered from a spray 

 nozzle, as compared with their performance when applied as a single drop- 

 let to the surface of a given solid. Whether this may Ijc due to momentum 

 of minute particles of liquid, or to molecular contamination of the surface 

 adjacent to a droplet, or to some other factor, remains to be seen. Certainly 

 there is evidence, also, that the character of the leaf surface may vary in 

 unsuspected degree as temperature rises. (l]\ C. O'Kane, J. G. Conklin, 

 E. C. Glovor. and Jl\ A. Westgatc — Purncll Fund.) 



Ovicides 



Two phases of the department's study of ovicidal performance were con- 

 cluded and published as Technical Bulletin 60, "1. Technique for Tracing 

 Penetration of Petroleum Oil in Insect Eggs. 2. Some Determinations of 

 Oil Penetration into Insect Eggs." 



Following the development of new technique for tracing the penetration 

 of petroleum oils into insect eggs by means of stains, determinations of actual 

 penetration of oils into insect eggs were carried through successfully. It was 

 definitely pro\"ed that with the insects studied and with the oil used, exten- 

 sive penetration does take place. 



In spite of an assumption to the contrary it w-as also found that fixing 

 fluids penetrate the eggs of insects. Penetration has been definitely proved, 

 and an attempt will be made to record it by photomicrographs. (W. C. 

 O'Kane — Adams Fund.) 



Apple Maggots Succumb to Oil 



Work on apple maggot control was continued at Wilton and at Durham. 



At Wilton a large cheesecloth cage wai? erected over the accumulated 

 pile of drops from last season, the drops having first been treated with old 

 crankcase oil. Only two apple maggot flies were recovered from this cage, 

 indicating that the oil treatment of drops was entirely successful in prevent- 

 ing emergence. {li\ C. O'Kane and J. G. Conklin— Hatch Fund.). 



Experiments with White Pine Fence Posts 



Effective and inexpensive treatment of white pine posts can be obtained 

 by the open tank method of creosoting according to studies over the five- 

 year period 1929-1934. 



Untreated posts used during that period showed 75% decay; brush 

 treated posts were 1 1 % decayed ; open tank created posts, pressure treated 

 posts, and ZMA (a zinc arsenic compound) treated posts all proved sound. 

 The decay in the first two groups \-aried from 3^ inch depth radial break 

 down to complete decay. 



The study suggests that there is a more profitable way to use straight 

 pine wood thinnings than for fire wood. (K. \V. Woodward — Hatch Fund.) 



