28 



appearance from the female, and are grown in hop 3'anls at about the rate of six plants 

 to an acre, for the purpose of fertilizing and maturing tlie hop blossoms. 



The Hop Aphis {Aphis humuli, Curtis). 



1. Hemiptera Homoptera — Aphid.?:. 



It would almost appear as if no catalogue affecting any particular plant could be 

 complete without referring to some species of Apliis, or Plant-louse, so ubiquitous and 

 destructive are these tiny creatures. We have already noticed in these reports * the 

 particular species that iufest the apple and the wheat, and have recounted the damage that 

 they oftentimes inflict. But when we come to the Hop we find that the Ajjhis, or "Fly" 

 as it is termed in England, is, par excdlence, its greatest enemy, and that the profits of 

 the grower depends very largely upon the presence or absence of the hordes of this minute 

 foe. As Kirby and Spence so strongly state, " the hop-grower is wholly at the mercy of these 

 insects ; they are the barometer that indicates the rise and fall of his wealth, as well as of a 

 very important branch of the revenue — the difference in the amount of the duty on hops (in 

 England, being often as much as J200,000 per annum, more or less, in proportion as theyfy 

 prevails or the contrary." In this Province we have seen the produce of a field of many 

 acres almost utterly ruined by this insect — the amount of hops, produced being dimi- 

 nished more than one-half below the average, and the quality of that which was gathered 

 very much impaired. 



The Hop Aphis resembles very closely in size and appearance the species that infest 

 manj' other plants. As we have already described similar species in these Reports 

 {\st Iifport, p. 77 ; 2nd Beport, p. 57), we need do no more than state that the enemy of 

 the Hop is green in colour, and about one-tenth of an inch in length when fully grown. 

 The accompanying illustrations display the shape and structure of the creature. Fig. 16 



represents a highly ^'S- ^'• 



magnified winged 



male above ; be- 

 low it, on the right 



hand side, a male 



of the natural size, 



and on the left a 



magnified female. 



Fig. 17 represents 



a female on a ver}' 



much larger scale. 



Notwithstand i n g 



the similarity in 



colour which ex- 

 ists between these 



insects and the leaves and stems of the Hop-plant, their presence may be immediately de- 

 tected by the blackish discolouration of the leaves below where they are at work. This 

 is caused by the continual exudation from the insects of a sweetish fluid called " honey- 

 dew," which is emitted from the two processes that project from each side of the extre- 

 mity of the abdomen. As we have remarked on a previous occasion, many insects, and 

 especially ants, are very fond of feeding upon this sweet substance ; the latter even go so 

 far as to perform upon the Aphis an operation analogous to that of milking a cow, for 

 the purpose of obtaining this sweet fluid. And not corttent with this, some species of 

 ants make a property of these Aphis cows, jealously guarding them, and using every 

 means to keep them to themselves. As related bj- Kirby and Spence : " Sometimes they 

 seem to claim a right to the Aphides that inhabit the branches of a tree or the stalks of 

 a plant ard if stranger ants attempt to share their treasure with them, they endeavour 

 to drive them away, and may be seen running about in a great bustle, and exhibiting 



Fig. 16 



* Firit A nnual Report — Inteeti aStcting the apple, p. 7? ; Second do — Iniacts affecting the wheat eiwpa, 

 p. 57. 



