220 



TREES AS GOOD CITIZENS 



gouged in the bark of young growth. 

 Upon hatching, the young penetrate the 

 bark and winter beneath it. In the spring 

 they resume feeding on the cambium or 

 inner bark. When fully grown, a few 

 weeks later, they bore into the wood and 

 into the pith, and tunnel a gallery in the 

 latter soft material. The presence and 

 activity of the borer are shown by dead 

 or dying limbs, swellings and dead patches 

 of bark, often cracked, on limbs or trunk, 

 fading foliage and the oozing of sap and 

 "sawdust" from points of attack. The 

 half-inch white grub will usually be found 

 in the burrow when an injured twig is split 

 open. 



arsenate in July, has been found effectual, 

 as has also the painting of trees with kero- 

 sene emulsion in April. 



Cottonwood Borer 



Habits This borer does much dam- 



and age, causing death or so weak- 



Damage, ening a tree as to cause it to be 

 broken off by the wind. The 

 grub is long and cylindrical, yellow col- 

 ored, and is hatched from eggs laid in 

 July and August, in small punctures in 

 the bark, at or below the ground level. 

 The young borers mine under the bark 

 and deep into the wood, throwing out 

 shredded sawdust. The mines thus made 

 at the base of the tree are responsible for 

 the weakness that makes the tree fall 

 before heavy winds. Sickly tops, and 

 collections of the shredded borings on the 

 ground, are the indications of the borer's 

 work. The borer continues his tunneling 

 for two years. 



Remedies. Destruction by digging 

 out the young borer is the 

 most successful remedy; or carbon disul- 

 phid, injected into the hole which shows 

 fresh sap and borings, will prove effectual 

 if the hole is promptly plugged and sealed 

 with grafting wax, putty, soap or clay. 

 Spraying the trunk with poisoned kero- 

 sene emulsion, or miscible-oil, is advo- 

 cated by some authorities for killing the 

 borers when young. 



Carpenter Worm 



(See description and remedies under Maple) 



Twig Girdler 



Oyster-shell Scale 



(See descriptions and remedies under Elm) 



SAP-SUCKING GALL INSECTS 

 Poplar Leaf-stem Gall-aphis 



Habits The gall formed by this 



and insect takes the form of a 



Damage, swelling of the stem, in which 

 a large brood of living lice is 

 born in midsummer. The aphids feed on 



Remedies. Unless the attack is 

 exceedingly severe, no treat- 

 ment is necessary. In extreme cases the 

 destruction of the insects may be accom- 

 plished by gathering the infested leaves 



