ATTACKING THE ROOTS. 15 



stroying these root-lice is the use of scalding-hot water freely 

 poured around the roots of the trees. If the trees are to 

 remain in the soil, the roots may be laid bare and the water 

 used nearly boiling without injury; but where they have 

 been taken up for the purpose of transplanting, and are 

 to be dipped in the hot water, the temperature should not 

 exceed 150° Fahr. ; under these circumstances from 120° to 

 150° would suffice for the purpose, A mulch placed around 

 the trees for some time previous to treatment has been found 

 useful in bringing the lice to the surface, where they can be 

 more readily reached by the hot water. Drenching the roots 

 with soapsuds has also been recommended, to be followed by 

 s liberal dressing of ashes on the surface. 



There are several friendly insects which prey upon the 

 root-louse. A very minute four- winged fly, Aphelinus mali 

 (see Fig. 15), is parasitic on it, and the larva of a small 

 beetle belonging to the Lady-bird family, Scymnus cervicalis, 

 feeds on it. This friend is difficult to recog-nize among- the 

 lice, from tiie fact that it is also covered on the back with 

 little tufts of woolly matter secreted from its body ; these 

 larvae are, however, larger than the lice, and much more ac- 

 tive, and may be further distinguished by the woolly matter 

 being of an even length, and arranged on the back in trans- 

 verse rows. The perfect beetle is very small, being but one- 

 twentieth of an inch long, with a dark-brown body and a 

 light-brown thorax. The beetle has been observed preying 

 on lice about the surface of the ground. 



A third friendly insect, probably the most efficient check 

 upon the increase of these lice, is known as the Root-louse 

 Syrphus fly, Pipiza radicum Riley, which in its larval state 

 feeds upon them. It is then in the form of a footless maggot, 

 which, when full grown, is about a quarter of an inch long 

 (Fig. 2, a), of a dirty yellow color, and usually so covered 

 with dirt and with the woolly matter of the lice it has de- 

 voured that it is not easily discerned. The eggs from which 

 these larvee are produced are laid by the fly (Fig. 2, c) in the 



