139 



lines, regulated L^razin"- and cleaning' out of dead trees — which 

 would more or less automatically control lig'htning' fires at the 

 start, the foresters believe. If these lightnino' zones were so 

 mapped they would doubtless show a markedly close relation 

 to certain types of topography, and sometimes more or less local- 

 ized sections of many forests. 



Next to campers and sparks from locomotives, lightning- ranks 

 third as the source of fires in the national forests. The records 

 of the Forest Service of the department show that for the years 

 1914-1918, inclusive, lig-htning- caused on the average 30 per 

 cent of all fires reported. However, during- 1920, a very unusual 

 season, over 50 per cent of the 6,078 fires that occurred in the 

 national forests w^ere set by lig-htning. 



SPLIT OR ROUND FENCE POSTS? 



Some people believe split fence posts last longer than do round 

 ones. Probably as large a number hold the opposite view. The 

 Forest Products Laboratory of the United States Department 

 of Agriculture says that one will last about as long as the other 

 if the percentages of heartwood and sapwood are the same in 

 both. If the percentage of sapwood is increased by splitting, 

 the split post will be less durable, while if the percentage of 

 heartwood is increased it will be more durable than the round 

 one. Exceptions to this should be made if the posts are of spruce, 

 hemlock, or any of the true firs, whose heartwood and sapwood 

 are about equally durable. 



If the posts are to be treated with creosote or some other 

 preservative, the round post is preferable to the split, because 

 of the comparative ease with which the sapwood can be treated. 

 Experiments at the laboratory demonstrate that the heartwood 

 faces on split posts do not, as a rule, absorb the preservative as 

 well as does the sapwood. 



FIG INSECT INVESTIGATIONS. 



By D. T. FuLLAWAY, Eiifonioloi^iisf. 



The investigations forming the subject of this report were 

 carried on in conjunction with similar investigations in the 

 Philippines, Fiji and Australia, and had as their object the 

 utilization of certain trees of the genus Ficiis (strangling figs, 

 banyans, etc. ) for reforestation in Hawaii. In these plants the 

 flowers are enclosed in a fleshy receptacle and are completely 

 dependent upon a single group of highly specialized insects for 

 fertilization. With the exception of the Blastophaga, introduced 

 for the Smyrna variety of the cultivated fig, none of these in- 

 sects exist in Haw^aii, and as they are absolutely necessary to a 

 free and natural spreading of species of Fi'cus, it was decided 

 to import them from the regions where they occur. 



A large number of the figs growing in Hawaii have come 



