RUMMER MEETING. 25 



NATURAL ENEMIES. 



There are several species of iusects that are either parasitic or 

 prey upon the apple tree wooly-aphis and tend to hold them in check. 

 It is doubtful, however, if they are of much value as a rule in check- 

 ing the root inhabiting form in this State, since they have not as yet 

 been observed in nature in sufficient quantities to cause any apparent 

 diminution in the number of aphis. It requires considerable search- 

 ing to find them at all, although most of the forms are frequently seen., 



A minute Ohalcistly {Aphelinus mali^ Hald ) is parasitic on the 

 wooly-aphis, and could if it ever appeared in sufficient numbers, 

 greatly diminish the number of aphids, but no case has been observed 

 where this has actually happened. This insect is so very small that it 

 'will escape the notice of the ordinary observer. 



The Koot-louse Syrphus-fly [Pipiza radicutn, W & R.) is frequently 

 found in the larva stage busily engaged in feeding on the root form of 

 the wooly-aphis. The adult fly might be mistaken by the orchadist for 

 the common house fly, but the larvae may be recognized among a 

 colony of aphids by the dirty, yellow-colored, spindle-shaped body 

 from one-fourth to one-half an inch in length, abruptly tapering at the 

 tail end and gradually tapering at the head end, and by the transverse 

 ridges encircling the whole. 



The larvae of a small Lady-bird beetle [Scymnus cervicalis) have 

 been found feeding on the aphids near the surface of the ground, but 

 as these larvae also excrete wooly matter which covers their backs, 

 it is difficult to distinguish them from the aphids themselves. 



The larvae of the Lace-winged flies {Ckrysopd) are often found 

 greedily devouring the aphids, but they, like the larvae of the lady- 

 bird beetle, seem to prefer to work in the open air, and are not 

 sufficiently numerous under ground to hold the aphis in check. 



Some spiders spin webs over the aerial colonies and devour the 

 aphids at leisure, and it is probable that our freedom from this form 

 of the wooly aphis is due largely to the spiders and parasitic and pre- 

 daceous insects. 



REMEDIES. 



The experiments with remedies to kill and control the wooly-aphis 

 of the apple tree were conducted in the laboratory and in the field. It 

 is not necessary to discuss the laboratory methods, since the field ex- 

 periments are final and were conducted in order to check and prove 

 the value of those carried on in the laboratory. 



The aerial form of the wooly-aphis can be easily killed by one or 

 two thorough sprayings with strong kerosene emulsion. If the aphis 



