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MRS. O. A. MERRITT HAWKES ON THE 



has a grey-green mealy exudation, which fills the stomata of the 

 larvae and so kills them. When a Victoria plum was covered with 

 this aphis, no larvae or imagines were ever fonnd among them, 

 and very few larvae of the Hover- fly, w-hich is probably an even 

 more prolific eater of aphis than the Coccinellidae. 



The presence of large numbers of Coccinellidse on the Stinging- 

 Nettle may be due to the fact that these insects are not univer- 

 sally carnivorous. C. septemjmnctata certainly eats the abundant 

 pollen and possibly other products of this plant. Donisthorpe 

 found that C. distincta ate the honey supplied to aiits, and I 

 have found C. septempiinctata eat the exudation from bean plauts 

 and Jerusalem artichokes in the autumn. IXiring the summer 

 I have observed A. hipunctata apparently eating the juice of rasp- 

 berries and split plums. 



The Adalia larvae in the first two instars liave to be fed with 

 minute aphis, as, although sufficiently pugnacious to attack large 

 aphis, the latter can easily sliake them off. 



Any species of aphis were used in 1918, but in 1919 practically 

 two species only —in early anmmQv xiphis pruui Fab., which attacks 

 da.mson-trees ; and for the remainder of the year Aphis fagi, 

 which lives only on the beech. Although the latter is slightly 

 woolly when full grown, -it is in the earlier stages veiy acceptable 

 to bipicnctaia. The copper-beech is attacked more frequently 

 than the green beech, and on the former numbers of hipunctata 

 are to be found all the summer. The supply of beech aphis has 

 the advantage of being fairly constant, as the leaves and branches 

 are so flat and so close together that it takes a great deal of cold 

 and rain to clean the aphis ofl' the tree. The flat leaves, which 

 do not wither readily, are very suitable in boxes. The aphis of 

 the rose {iSiphonora rosa') and of the nettle {Aphis urticia) both 

 die quickly in boxes, presumably owing to the wilting of the thin 

 leaves of the food-plants. 



In August 1920, after a variety of experiments, I found that 

 the adults will eagerly eat pounded dates, upon which they can 

 live for months. The newly hatched larvae cannot use this food 

 at all, but I succeeded in bringing one larva from the second 

 instar to the perfect insect on dates alone, the imago being of 

 average size. Most of the older larvae Jvept alive on this diet for 

 some time, but did not giwv much and ultimately died. 



I have obtained the best results by feeding in closed boxes. 

 The boxes must be opened every day, not only to introduce fresh 

 food but also fresh air, which is of paramount importance to this 

 species. Great care has also to be taken to remove all mouldy 

 leaves. A mould (probably Gladosporium aphidis Jhlim) quickly 

 grows on the honey-dew produced by the aphis, especially that 

 found on beech and sycamore leaves. This mould fatally attacks 

 the larvae. It first appears on the thorax, but its method of 

 producing death is undetermined. 



The main difiiculty of rearing is the cannibalistic habit of not 

 only A. hipunotata^ but also C. septempiinctata, C. variabilis, and 

 H. \4:-2)nnctata. The larvae eat eggs and one another in either 



