6o6 
The Destruction of Noisome Insects . [October, 
of man’s enemies, and so many of his most valuable friends, 
that we might well pause before attempting any widespread 
application of Pyrethrum powder to our fields and gardens. 
Amongst the Hymenoptera are included not merely the 
honey-bee, but the various humble-bees, &c., which play so 
important a part in the fecundation of many flowers. Here, 
too, belong the ichneumon-wasps which so largely contribute 
to reduce the number of caterpillars. Hence any agent 
generally fatal to the Hymenoptera will require care and 
judgment in its application. If it is fatal to ants it may be 
of great value in checking the ravages of the leaf-cutting 
species, and of those which protect and even introduce 
Aphides and scale-inseCts. 
On the other hand, we are told, as among the results of a 
course of experiments extending over three years, that 
Pyrethrum has no action upon the eggs of inserts, or upon 
pupae enclosed in hard cases. Many hairy caterpillars also 
remain unaffected. 
Hence, though the plant can doubtless be grown to ad- 
vantage in most sub-tropical countries, we must not expeCt 
too much from its application. 
