162 ZOOLOGY. 



in half a gallon of hot water ; ^ lb. of quassia chips 

 extracted for twelve hours in 5 quarts of rain water, 

 and the fluid thus obtained boiled and filtered. It is 

 then added to the soap water, and the whole brought up 

 to 10 gallons by addition of rain water). Spraying 

 with one of the above-named fluids must be renewed 

 in a short time, so as to reach ail the aphides wher- 

 ever possible ; if even a few remain untouched, there 

 will soon be a large number again. A warm evening 

 is best for the spraying. Infested plants can also be 

 strewn with finely powdered substances, or these may 

 be scattered over them by means of a small bellows. 

 Since such substances should remain on as long as 

 possible, they should be used after rain or early in the 

 morning, when the dew is still on the leaves. Among 

 powdered matters suitable for the purpose, the follow- 

 ing may be named : gypsum, lime, tobacco, wood-ash, 

 insect powder (prepared from the flower-heads of 

 Persian species of chrysanthemum and from tansy 

 heads). It must also be pointed out, that these 

 remedies must be employed as soon as the insects 

 begin to show themselves in considerable numbers ; 

 it is not desirable to delay till the infestation has 

 made considerable headway,- as it is then much more 

 difficult to get a satisfactory result. In some cases, 

 it is desirable to cut ofl" and burn or otherwise destroy 

 much infested parts, or those parts on which the in- 

 sects first begin to multiply {e.g. early cutting off of 

 the tips of the stems in field and garden beans). 



The species of aphis which most commonly occur 

 upon cultivated plants are : — The Bean Aphis {Aphis 

 papaveris), ^- inch, black ; on the tips of the stems 

 of field and marsh beans, also on poppy, turnips, 

 lettuce, and on several wild composites and umbelli- 

 fers. The Pea Aphis (Aphis uhnavicB), ^ to ^ of an 

 inch long ; green ; July to September on peas, chickling 

 peas, and several wild leguminous plants; very de- 

 structive. The Corn Aphis {Aphis cerealis), j\- inch. 



