342 ANNUAL REPORT. 



upon which they are gathered in the cool of the day with an insect 

 net, occasionally inverting and shaking this over a bucket of water 

 and kerosene. Two topical applications have been found deadly to 

 them, one of them especially so. A single dusting with pyrethrum 

 (or Persian insect powder) has been found sufficient to kill event- 

 ually every insect exposed to it. This may be used either mixed 

 with ten parts of flour, or suspended in water and sprayed or 

 sprinkled on the bugs at the rate ofabout fifteen grains of powdered 

 pyrethrum to the pint of water. As this substance can now be had 

 from the importers for about forty-five cents a pound, it is well 

 within the limits of economical use for the protection of horticul- 

 tural products. 



The kerosene emulsion, made by a thorough churning of equal 

 parts of kerosene and sour milk until a permanent cream is pro- 

 duced, is almost, but not quite equally efficient.. For use, it should 

 be thoroughly mixed with ten parts of water and sprayed or 

 sprinkled on the plants. 



A full and elaborate account of this insect, illustrated by figures 

 of all its stages will be given in the forthcoming report of the state 

 entomologist of Illinois. 



PROF. BURRILL AND MR. PEFFER ON BLIGHT. 



In the Horticultural number of the Fanner's Review^ of Chicago, 

 published February 28, 1884, is an article on Blight, by Prof. T. J V 

 Burrill, of the Illinois College of Agriculture, in which the imme- 

 diate and active agency producing the disease, that which causes 

 the changes in the tissue of the wood and bark, is described as "a 

 living, self-multiplying organism classed among the bacteria^ or, as 

 often inappropriately called, 'disease germs.' '" 



Professor Burrill says : "There is absolutely no doubt of the 

 truthfulness of this statement. Hundreds of persons have seen the 

 destructive little things through microscopes of high powers, and 

 wherever the apple and pear blight is in progress they can always 

 be found in great numbers. The disease is easily produced artifi- 

 cially by inoculation — taking the organisms from infected trees 

 and putting them in the living bark of healthy ones, by the aid of 

 a pointed knife or needle. When thus introduced the bacteria de- 

 stroy the contents of the living cells without attacking the cell 

 walls; a kind of fermentation is set up and the part is killed. In 



