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A New Enemy of Douglas Fir. 



[JAN., 



of the individual Megastigmus being somewhat extended, or 

 perhaps also by the overlapping of generations with issue of 

 adults at different times during the summer. An endeavour will 

 be made in 1906 to clear up some of these points in the biology. 



Wachtl in Mid-Europe bred out, in 1893, from seeds of the 

 Douglas Fir, from March 30th to May 4th, a large number of 

 M. spermotrophus of both sexes, the females predominating. 

 Mr. Crozier got in ten days from seed blown through the fan 

 in dressing or cleaning 182 adults, of which 142 were males. It 

 is possible that this excess of males may be due to the fact 

 that the males, being smaller than the females, the seeds 

 enclosing the males, being somewhat lighter, would be the more 

 likely to be blown through in dressing. I bred out from a very 

 small quantity of seed in May and June thirty females and 

 nineteen males. 



The native home of the Douglas Fir, known also as the 

 Oregon Pine and Columbia red wood, is Western North 

 America, where it extends over an area of 50,000 square miles, 

 between 43 deg. and 52 deg. latitude. Megastigmus has doubt- 

 less been introduced to Britain in seed from the native home of 

 'the tree. To what extent the insect may be present in Britain 

 we cannot yet estimate, as comparatively few estates take 

 advantage of the seed produced on the Douglas Firs grown on 

 them. I would be very glad, in view of a later communica- 

 tion, to receive material from any estate of Douglas Fir or other 

 cones for examination. 



Protection and Remedy. — The insects are so small, and the 

 number of cones on the tree may be so great, that direct 

 measures to prevent egg-laying do not seem very practicable, yet 

 it is worth keeping in mind that close allies of these insects are 

 considered as amongst the easy prey of the collector, good hauls 

 being got by netting and sweeping and beating the trees. Such 

 sweeping or beating where Megastigmus brought itself within 

 reach would be certain to account for numerous adults. Any 

 adults that are seen on the seed-beds should also be destroyed. 



Against the insect in its various stages in the seed, however, 

 measures can probably be adopted with success. 



The cones should be gathered as soon as ripe (the latter half 

 of October) and should at once be subjected to such treatment 



