Sept. 1895.] 



INJURIOUS INSECTS AND FUNGI. 



173 



Continental foresters dig trenches by the sides of young fir 

 "breaks," or "sections," from 12 to 15 inches wide and about 

 the same depth. Freshly cut branches of fir or freshly cut 

 pieces of fir wood are put into them to entice the beetles, which 

 may be stamped to death, or collected by women and children. 

 In four years, from 1880 to 1884, no less^than 9,852,600 beetles 

 were collected in seven Royal Forest districts of Saxony.* 



Traps of freshly cub fir wood may be placed with the rind 

 downwards in infested plantations. Also pieces of fresh bark 

 will entice the beetles, and bundles of fresh fir branches are 

 particularly attractive to them. The traps should be frequently 

 examined and the beetles collected. Such traps are extensively 

 adopted in the continental pine forests. 



Gathering the beetles from the young firs by hand is practised 

 abroad, and in Scotland. The beetles are large and easily seen, 

 and being sluggish in the daytime can be taken without much 

 difficulty. In the plantation in Scotland alluded to previously, 

 8,000 beetles were gathered in this way, but the mischief had 

 been then practically done. Smearing the stems of the trees 

 with some sticky and unpleasant material, such as petroleum oil 

 or carbolic acid mixed with soft soap, would keep the beetles 

 from crawling up the trees. This would be a costly process, 

 and it is not clear that the beetles might not fly on to the lower 

 branches of the trees, though they are not easily moved to flight, 

 and fly heavily and awkwardly. 



The Cucumber and Turnip Mildew {Oidmm balsamii). 



This fungus has been somewhat unusually prevalent this 

 season on cucumber plants, both in frames and houses, and in 

 the open air. It appears in the form of white patches upon the 

 upper surfaces of the leaves, and, in circumstances favourable to 

 its -development, it spreads very rapidly and soon afifects the health 

 of the plant. The leaves dry up after a time, the blossoms 

 fall oflf, and the cucumbers that had formed cannot grow out 

 properly. 



Oidium balsamii is also frequently seen upon swede turnips. 

 The leaves of whole fields of these are powdered with white 

 mildew, which comes off upon the clothes of persons walking 

 through the turnips. 



It is easily distinguished with a microscope by its peculiar 

 barrel-shaped conidia or spores. The mycelium, like that of 

 many of the Erysiphce, does not penetrate into the leaf, as in 

 the case of the potato fungus. I'ts- filaments traverse the upper 

 and under surfaces of the leaves, and, forming a thick mass of 



* Lehrbuch der Mitteleuropdischen Forstinsektenkunde^ Von Dr. J. F. Judeieh 

 und Dr. H. Nitsche. 



D 2 



