30 INSECTS NOXIOUS TO AGRICULTURE. 



is believed that the information here given may be accepted and 

 relied on. 



Some of the substances here given are manifestly unsuitable 

 for general use on account of their expense, at any rate in the 

 open air. Yet it is well to include them,, as they are all sug- 

 gested in some work or other, or in the replies of gardeners and 

 fruit-growers to parliamentary inquiries ; and the objections to 

 them ought also to be known : 



1 . Alcohol. Will certainly kill any individual insect ; but 



" sprayed over scale-insects produced no apparent 

 effect" (Comstock). 



2. Ammonia. Whether used pure (diluted) or in urine, 



damages the plants much more than it does the 

 insects (Hubbard ; Comstock) . 



3. Ashes. Powdered, or mixed with lime, salt, soot, &c. Of 



no value whatever (Hubbard; Personal experiment). 



4. Carbolic acid. Of no avail, either as spray or brushed 



on, unless used in such strength as to seriously 

 damage the tree (Hubbard ; Riley ; Comstock) . 



5. Castor-oil. Has been found efficacious in cleaning haw- 



thorn-trees at the Agricultural College, Lincoln (T. 

 Kirk). It was mixed with soot for some unexplained 

 reason. The time of the year when it was applied is not 

 stated ; but the author's experiments seem to show that 

 castor-oil does not effectually kill the eggs. Still, it is 

 doubtless a valuable remedy if applied repeatedly, so 

 as to kill larvae and adults, supposing it to be suffi- 

 ciently cheap. 



6. Cole's Insect-exterminator. Apparently a mixture of about 



2 parts of (t green soap " with 100 parts of strong 

 alcohol. It is " effectual as an insecticide, and harm- 

 less to growing plants ;" but " the cost is too great, 

 except on a small scale, as in conservatories " (Com- 

 stock) . 



7. Gasoline. Seems to have been used in California on 



pear-trees : result, doubtful (New Zealand Parlia- 

 mentary Papers : Codlin Moth Committee Report, 

 1885, page 8) . 



8. Gishurst compound. Very favourably spoken of in many 

 quarters. In New South Wales it has been found 

 efficacious on orange -trees against Aspidiotus coc- 



