100 



TRANSACTIONS OF THE ILLINOIS 



instances of this kind, where the trees received were so infested tliat 

 the receiver was strongly tempted to burn them, and naturally 

 enough his feelings toward the firm sending them out were not 

 cordial. 



THE WOOLLY APHIS. 



Fig. 1." 



Schizoneura lanigera^ Haus. 



There are frequently found on the limbs and trunk of young 

 apple trees, masses of a white woolly substance, very similar to what 

 has been so common daring the last few years on the limbs of soft 



maple trees infested by 

 the maple bark louse. If 

 one of these masses be 

 examined, there will be 

 found beneath it one or 

 more small yellowish 

 plant lice. These are 

 what have for a long 

 time been popularly 

 known as the Woolly 

 Aphis (Schizonenra ht- 

 nigera). There are two 

 forms of the insect, one 

 attacking the roots, tbe 



-WOOLY Aphis, enlarged and natural size. presence of which may 



be easily detected by the knotty appearance of the roots infested, and 

 one attacking the twigs and trunk. These latter are the ones most 

 commonly seen, and secrete the most of the woolly substance just 

 mentioned. In either situation the effect of their presence is to 

 weaken the vitality of the tree by sucking its sap. The eggs are laid 

 in autumn on the bark, and remain in this condition through the 

 winter. Hence the insect is very liable to be disseminated through 

 the agency of young nursery trees. This pest is very common in 

 some of the nurseries of this and adjacent states, and is doubtless 

 being continually reintroduced into a great many localities. I have 

 seen young apple trees that were being heeled in, preparatory to 

 transportation, that showed at nearly every node on the trunk the 

 white woolly secretions of the insect. 



EEMEDIES. 



The same ground should not be planted to apple stock twice in 

 succession, on account of the too favorable opportunities thus given 

 for the undue multiplication of this and other insects. Though ro- 

 tation will not wholly prevent the ravages of any of these pests, it 

 will help so to do, and should be practiced wherever possible. In his 



