344 Wisconsin State Hoeticultueal Society. 



violent symptoms — vomiting and spasm?, followed by convul- 

 sions and insensibility. 



The insect powders of commerce are the powder^fd flowers of 

 different species of Pyrethrum. Those of P. caineum and roseum 

 were introduced twenty or thirty years ago under the name of 

 Persian insect powder, and, within a much more recent period, 

 those of P. cinnerisefolium under the name of Dalmatian insect 

 powder. Both of these powders are good insecticides, but the 

 Dalmatian is much the more active, and, hence, commands the 

 highest price. The pyrethrums are hardy plants, which bloom 

 abundantly the second year from seed. The powder is prepared 

 from the half opened flowers, gathered during dry weather, and 

 dried in the shade under cover. 



House flies are very sensitive to the influence of these powders, 

 and a few puffs of the dust, blown into the air of a room, with 

 closed doors, the discharges being directed towards those parts 

 where flies congregate, will stupefy and paralyze them within a 

 few moments so that they will all be found on their backs, strug- 

 gling on the floor, and injured to such a degree that but very few 

 ever recover the power of flight again. They are also extremely 

 useful in destroying cockroaches and other household pests, and, 

 used in the same manner in a green-house, but a little more 

 freely, they have a similar effect on plant lice. 



Prof. Kiley, giving the result of some experiments with this 

 California pyrethrum powder on the cotton worm, states that the 

 slightest puff of the powder causes the worm to drop almost 

 instantly from the plant, and insures its speedy death. Besides using 

 the powder pure he used i*: mixed with a small quantity of rosin, 

 and also tried it diluted with ten times its weight of flour, and 

 says that when thus diluted " it produces equally good results as 

 when pure." This is indeed a most unexpected result, and it 

 seems difficult to understand how a powder of this sort can, when 

 mixed with ten times its weight of insect powder, be equally 

 efficient with the undiluted substance. It is also asserted that a 

 strong decoction of the powder with water produced no appreciable 

 effect, but that an alcoholic extract mixed with water in the pro- 

 portion of one part to fifteen or twenty of water, and sprayed on 

 the leaves, was very efficacious in killing the worms. 



