One fifth of a thimble per acre

[Kenelm Philip]

> sufficient to kill houseflies, but not larger insects like butterflies or
> even drosophila.

	_Even_ drosophila? These are the small fruit flies so beloved of
genetics workers--and if they are larger than house flies then my eyes
have been playing tricks on me all my life!

	If spraying pyrethoid insecticides at low concentrations kills
house flies but not the (smaller) fruit flies, then there is clearly a
large variation in susceptibility among _diptera_, not necessarily related
to size. No extrapolations to lepidoptera can safely be made--one would
have to conduct tests. Have such tests been made?

							Ken Philip
fnkwp at uaf.edu




 
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