INSECT PESTS AND DISEASES. 183 



apple. The trees are also destroyed by canker in the 

 same way as the apple (which see). 



PEAR LEAF RUST (Eoestelia cancellaia) . The mycelium 

 of this fungus lives in the interior of the leaves of the 

 pear tree in one stage of its existence, causing rugged 

 elevations or swellings upon them. The blotches result- 

 ing are at first pale in colour ; but as the fungus ripens, 

 and the peridium bursts along its sides, to allow of the 

 dissemination of the spores, they become rust-red, and 

 show themselves on both sides of the leaves. 



REMEDIES. There is really no cure for this pest, owing 

 to its living beneath the epidermis of the host plant. The 

 attack may, however, be greatly mitigated by promptly 

 collecting all blistered leaves on the earliest appearance 

 of the evil, and burning them before the spores are ripe, 

 that is before the blotches assume a rusty hue. Badly 

 infested trees may be destroyed, to prevent the disease 

 spreading to healthy ones, a process greatly aided by 

 the wind, when the spores are ripe. Juniper bushes 

 must not be allowed to grow in the vicinity of orchards, 

 as the fungus is known to live upon Juniperus Sabina, 

 in one stage of its life cycle. 



The Plum. 



PLUM APHIS (Aphis pruni). Great damage is often 

 done to the trees by this troublesome aphis, which in- 

 creases at an alarming rate, causing the leaves to curl 

 up, and covering the foliage beneath with a viscid exuda- 

 tion, which soon becomes black, attracting swarms of ants, 

 wasps, and flies, which complicate the mischief by attack- 

 ing the fruit. The wingless forms bringing forth live 

 young, vary from green to olive brown : the winged ones 

 are bright green, and both are covered with a mealy 



