564 THE AGRICULTURAL JOURNAL. 



The Black Peach Aphis. 



MYZUS CERASI, FA BR. 

 By Claude Fuller, Government Entomologist. 



\ .V10NG many other items of interest in 

 the pages of the most recent annual 

 report of the Cape Government Entomolo- 

 gist, mention is made of the fact that a 

 considerable number of peach trees from 

 Australia were seized and destroyed in 

 Cape Town because they were infested 

 with black aphis. Such drastic measures 

 lead one to the natural conclusion that 

 the pest has not gained a foothold in the 

 Old Colony. iSuch a happy state of 

 affairs does not, however, exist in Natal, 

 as, upon several occasions during the 

 past two years, my attention has been 

 drawn to the insect in different parts of 

 the Colony, and I cannot but think that 

 it is much more abundant this spring 

 than formerly. Still the aphis is not by 

 any means as widely spread as it might 

 be, so, perhaps, by drawing attention to 

 it now, those who may find it on their 

 peaches or nectarines will make an effort 

 to keep it under control. 



In common with numbers of others, 

 this pest is an introduction from abroad, 

 and whose original home is supposed to 

 have been in Europe, where it occasions 

 much mischief among cherry trees, a cir- 

 cumstance from which is derived its 

 specific name cerasi {cerasus, a cherry 

 tree\ 



Peach aphides in general form and 

 habits much resemble the many other 

 aphides common to the farm and garden, 

 such, for instance, as the corn aphis, the 

 rose aphis, and the turnip aphis. In this 

 respect they are small, soft-bodied crea- 

 tures of social habits, and feeding upon 

 the juices of the host plant which they 

 imbibe through a rostrum or beak suited 

 for piercing the tissues and pumping up 

 the juices. In common with other 

 aphides also, the damage which results 

 from their -"attack is due to the huge 

 swarms in which they occur, and the 

 multitudes which infest a single plant 

 have their origin in the marvellous repro- 

 ductive functions belonging to this group 

 of insects. These procreative powers, 

 coupled with an extraordinary prolific 

 nature, readily explain the rapid increase 



of aphides, and whilst it would occupy 

 far too much space to give a full explana- 

 tion of them, it may be briefly stated that 

 the insects have a sexless reproduction for 

 the greater part of the year. The creatures 

 possessing this remarkable faculty are 

 known as "stem-mothers," and they 

 produce young possessing similar func- 

 tions with their own, and this goes on for 

 many generations. These "stem-mothers " 

 arrive at maturity — in the case of the 

 black peach aphis — when ten days old 

 (September and October), and give birth 

 to an average of between five and six 

 young per day uninterruptedly for about 

 20 days, at the end of which time, from 

 observations which I have made, each 

 " stem-mother " is the progenitor of about 

 2,813, and in seven weeks is the grand 

 parent of 12,210 aphides and the great 

 grand parent of some thousands more. 



In this connection Reaumur, an eminent 

 naturalist, calculated that one aphis may 

 be the mother of 5,904,900,000 individuals 

 during the six weeks of her existence. 



Having once conceived the prolific and 

 rapid powers of multiplication possessed 

 by these insects, the farmer can readily 

 realize the probable outcome of a small 

 patch of aphis on any of the plants under 

 his care, and he can also appreciate the 

 value of a treatment which, if it doesn't 

 destroy every aphis, will destroy fifty to 

 eighty per cent, of them. 



Winged and Wingless Aphides. 



The effect of the attack of the black 

 peach aphis is pai'ticularly noticable in 

 the spring, when the new growth of 

 foliage is usually much stunted and de- 

 formed and encrusted with multitudes of 

 the lice. If such an infected twig is ex- 

 amined, the insects will be seen in several 



