1 894-] 



THE BRITISH NATURALIST. 



I2 5 



buds of the plum and apricot. By the time the leaves and blossoms 

 were fully out Aphis pmni literally swarmed over them. The young 

 leaves became at once curled and shrivelled, and the blossom itself was 

 also attacked, a somewhat unusual occurrence. Generally this fruit 

 louse does not appear until after the bloom is set, and even then often 

 does much mischief, sometimes entirely spoiling what little fruit forms, 

 by their black excreta and gummy honey dew. This year I am afraid 

 in many places they will materially affect the formation of the fruit, if 

 they continue to increase at the present rate. The first generation 

 that makes its appearance in the spring is the apterous viviparous 

 female, which are at first pale yellowish green, but later become 

 darker, with dark mottlings and a dark dorsal stripe ; some specimens 

 become almost brown in hue. During the present spring I noticed they 

 gave rise to living young with extraordinary rapidity. Two isolated 

 females (wingless) from the ist to 18th of April, produced no less than 

 107 young. I only followed tha reproduction by one of these second 

 generation, and this I found bred with equal rapidity after ten days. This 

 rate of increase, although greater than usual for this time of year, is noth- 

 ing compared to later in the season and in other species. Prof. Webster 

 (U.S.A.) sends me a paper in which he records that one wingless 

 female of the Apple Louse in 21 days gave rise to 89 young ! For 

 the last ten years certain greengage and plum trees at my home 

 (Kingston-on-Thames) have suffered more or less from this blight, in 

 spite of various methods of prevention, by way of destroying the ova, 

 which the oviparous females deposit upon the stem and twigs in the 

 autumn. I find this year that by spraying the trees with an emulsion of 

 paraffin or kerosene, just before the buds burst (that is about the time 

 when many of the ova are ready to hatch), many of the embryos are 

 destroyed. I learn from correspondents that this aphis is very abundant 

 in many parts of the country, and already it may have done much 

 harm. The pupal form generally makes its appearance about May. 

 The pupae are very much like the wingless females, but if they are 

 carefully noted, rudiments of wings are found on each side, and there 

 are yellow markings upon the upper side of the body. The pupal form 

 gives rise in the summer to the second or winged-female, which is pale 

 yellowish-green, with the prothorax and three thoracic lobes dark 

 green, and with dark green markings on the abdomen ; the wings are 

 hyaline and delicate, and have green stigma, cubitus and insertions. 

 Towards autumn true males are produced ; they are likewise winged, 

 but are yellowish-brown in colour. Miss Ormerod says the males may 

 appear in November, but I have never seen them so late ; as a rule, 

 the latter end of September and October are the times they appear. 

 About this time also the last form of female, namely, the oviparous 

 wingless creature, is developed. 



