Jnly 3, 1ST1. ] 



JOUENAL OF HORTICULTURE AND COTTAGE GARDENER. 



35 



tave been literally swarmed with Aphis Pruni, scarcely a leaf 

 escaped being curled up to the midrib. Cherries were not free 

 of the black fly (A. Cerasi), and Gooeebeny and Currant 

 buthes were severely attacked with Aphis Eibis, and Rose 

 bufhes were smothered with A. RoEie. Whenever aphides are 

 unusually abundant the weather is mostly dry and cold, and 

 whenever there is a great plague of aphides honeydew is de- 

 posited proportionately. I know some of your close observers, 

 as the Kev. W. F. Eadclyffe, deny, or appear to deny, that 

 honeydew is due to and has its origin in insects. The Editors 

 I think are justified in pronouncing againet us (for I do not 

 stand alone) on this point ; but whatever the appearances are, 

 for or against our ideas, we must all give way to those facts ever 

 at the command of the attentive observer. In no instance 

 have I noticed honeydew without being able to iind insects 



(aphides) infesting plants, shrubs, or trees, directly over or in 

 close proximity to deposits of honeydew. 



To insect agency any observing person may ascribe the 

 formation of honeydew, no other agency natural or artificial 

 causing it to be deposited. The aphides and scale (Coccus) 

 tribe of insects do not exist on plants without creating honey- 

 dew ; it is deposited on all surfaces under or near these in- 

 sects, be they leaves of plants, walks, paths, soil, stages. It 

 is not found on the parts of plants above the insects, but 

 may be found on surfaces at a considerable distance from the 

 feeding ground of the aphides, yet always lower than it. It 

 falls, as everyone knows, and is never found on surfaces above 

 the aphis-attacked trees. In a plantation of bush fruit trees 

 that may have some standard trees of a kind not infestf-d 

 with aphides, whilst the bush fruit trees are, the latter will 



Fig. 10.— SPltING BJiDDINa AT ELSTTAM HOUSE, 



have a great quantity of honeydew on the leaves, especially 

 t!ie lower ones, but the insects being at the points of the 

 shoots the upper part of the bushes may also have, and usually 

 have, a slight deposit of honeydew, the standard trees being 

 perfectly free. If the honeydew is not caused by insect agency, 

 why is it present on the bush trees and net on the standard ? 

 I have two Apple trees in a plantation of " berry " trees ; honey- 

 dew is on the latter, the Apple trees are free. Another plant- 

 ation or quarter is free of honeydew on the low-growing sub- 

 jects free of the fall from two standard Plum trees which are 

 attncked with aphides ; the deposit of honeydew is on the leaves 

 of the Plum trees, and on those of the plants under and for a 

 short distance from the aphis-attacked trees, but the other 

 subjects of the quarter are clear of the deposit. Then we 

 have some groups of Roses near clumps of shrubs ; the Roses 

 are attacked with aphides, and the foliage clammy with honey- 

 dew, which is not on the grass, the shrubs, or any part of the 

 surroundings. 



It may be urged that honeydew is a secretion of the plants, 

 the aphides not being the cause but the consequence of the 

 attack. The honeydew is deposited on the upper surface of 

 leaves, never on the lower, and the aphides come to feed on 

 the under surface, and suck the honeydew through the leaf. 

 It is not a secretion of the plant due to insect agency ; for if 

 we take a plant infested with aphides, free it of them, cleansing 

 the leaves and stem of honeydew, making the plant perfectly 



clean, oa covering it with a hand or beU-glass we shall not 

 find any deposit of honeydew in twenty-four hours. This 

 shows that the secretion, if of the plant, ceases with the removal 

 of the insects, and gives ground for considering the honeydew 

 not a secretion of the plant ; for were it so, and arose from 

 the punctures of its tissues by the insects, it is highly probable 

 that the plant Vy-ould continue to secrete the fluid, for a time 

 at least, after the removal of the insects. 



Let us introduce on the plant under the glass two or three 

 aphides, the kind peculiar to the species, and cover again with 

 the glass. Within tweuty-four hours we have on the surface of 

 the leaves immediately under the insects dots of honeydew, 

 proving conclusively that its presence is due to the insects, 

 that it is not a secretion of the plant attracting the insects, 

 nor 11 secretion of the plant caused by the insects, but tho 

 secretions of the insects. Anyone can put to the test these 

 simple facts, demonstrating on a Rose bush in a pot, or a 

 Pelargonium, the cause of honeydew as clearly as were he 

 master of all the mysteries of vegetation. 



The cause of honeydew may appear but a matter of little or 

 no importance to the cultivator, but it is, nevertheless, not 

 altogether insignificant. If it were established that honeydew 

 is a secretion of the plant not attributable to insect agency, it 

 would follow that the condition of the plant caused it to bo 

 attacked by insects, and we should then only have to keep ths 

 plants healthy — apply that which nature does not afford, and 



