45 



of Clu'inistry of this Department. Further account of them here is 

 therefore uunecessary. 



Important injuuious insects, C. P. Gillette, M. Sc. (pp. 161- 

 190). — This contains short acicounts of the most important insect pests 

 of Iowa, and the means for their i)revention or destruction. The fol- 

 h)\ving are described: Cut-worms {Noctuidw spp.) sod web-worm {Cram- 

 bus exsiccatus), wire-worms (Elateridce si)p.), corn root-worm {Diahrotiea 

 longiconiis), cabba<ie worms {Pieris rapw and protodice, and Plusia 

 brassicw), striped cucund)er-beetle {Diabrotica vittata), tlat-headed borer 

 {Crysobothris femorata), round-headed hoiev (Saperda Candida), codling 

 moth [Carpocapsa pomoneUa), phim curculio {Conotrachelus nenuphar), 

 plant-lice {AplddkUv. spp.), red spider [Tetranychus telarim), cattle-lice 

 {Hemwtopinus eurystermts and Trichodectes scalaris). Among" the ex- 

 periments with remedies reported, are the following: 



For the striped cncumbcrbeetle. — Ashes, lime, and hellebore were used, 

 with unsatisfactory results. Pyrethrum dissolved in water was ineffect- 

 ual, but when applied dry in the early morning was a "complete suc- 

 cess." London purple mixed with flour in the proportion of 1 to 20, and 

 dusted over the plants, afforded a partial protection, as did "Oxide of 

 Silicates," a patent insecticide whose chief ingredient is stated to be 

 plaster of Paris. A few plants in a garden may be protected by cover- 

 ing " one end of open boxes with cheese-cloth, and setting the boxes over 

 the hills," or "thin cloth or paper may be laid over the plants and the 

 edges held down with clods or stones." 



JPorj;Zrt7^^?^ce.— Kerosene emulsion (2 percent strong) is recommended 

 as the most useful insecticide against plant lice, if applied thoroughly. 



For cattle lice. — Kerosene and lard, kerosene emulsion (8 per cent), 

 potato water, and pyrethrum were successfully used. 



Experiments icith pyrethrum (pp. 190-193). — This is an account of 

 tests made "for the purpose of proving or disproving" whether it is 

 necessary to keep " this powder in closed vessels in order to retain its 

 strength," and whether good results can be obtained by making a de- 

 coction of the powder in boiling water. 



As a result of my experiments it seems safe to conclude, at least until more care- 

 ful and exhaustive experiments prove to the contrary, that when it is desired to 

 use pyrethrum in water without waiting twenty-four hours it can be prepared in , 

 boiling water (in which case I would advise boiling for five or ten minutes) and as 

 good results obtained as with the cold-water extraction, and second, although it is 

 always advisable to keep the powder in tight receptacles it does not seem possible 

 that the powder loses its strength very rapidly when exposed to the air. 



Potato-icater. — An account of the successful use of strong potato- water 

 as an insecticide for plant-lice. 



The parings were chosen for the experiments upon the supposition that if there 

 was any insecticidal property in the potato it would be in the skin, but perhaps the 

 paste formed by the starch of the potato in water may have clogged the spiracles and 

 done the killing instead. 



