78 



and become bent and hidden by rolled up curled leaves. The 

 fruit fails or falls away owing to the destruction of the leaves. 



Theobald writes of nine species found on the genus Ribes ; 

 of these four may be mentioned here. 



Aphis grossulariae, Kalt. Is found on the currant and 

 gooseberry from May onwards. Later it leaves these plants 

 to fly to other species, but the complete year's round of life 

 is still in doubt. On the currant and gooseberry this Aphis 

 attacks the leaves and the young wood. The leaves get 

 crowded together and overlap and the Aphides are thus 

 sheltered from any spray applied too late. 



Winter is passed on the currant and gooseberry in the egg 

 stage. The eggs hatch and from April onwards the wingless 

 females are found on the under surface of the leaves which 

 show green, yellow, and red blisters. The winged individuals 

 appear in summer and fly to the lettuce; they have also been 

 found on nipplewort, sow-thistle, and guelder-rose. The return 

 to the currant and gooseberry takes place in autumn. 



Myzus ribis, Linn. This species is found on the currant 

 and gooseberry from May to July. It gives rise to blisters 

 on the leaf, as with the previous species, and it often causes 

 the leaves at the apex of the shoots to curl. Winged females 

 migrate in late summer but details are lacking. 



Macrosiphum lactucw, Schrank. This species found on 

 red and black currants migrates to the lettuce and other 

 composites at midsummer and returns to the currant in the 

 autumn. 



Methods of Control. Aphid attacks on gooseberry or 

 currant are not easy to deal with, for until the injury becomes 

 apparent the presence of the pest is seldom realised. Early 

 spraying, before leaves have become curled or shoots distorted, 

 is effective and any good contact insecticide, such as nicotine 

 and soap or paraffin emulsion, may be used (for formulae see 

 Leaflet No. 308, Plum Aphides). When (in small gardens) 

 young growth is attacked at the tip, it is often better to bend 

 over the shoot and dip the tip into a vessel of insecticide 

 instead of spraying, as by the latter means it is difficult to wet 

 aphides in a "rosette." Primings should always be burned. 



THE CURRANT BOOT AND ELM LEAF APHIS. 



Schizoneura ulmi, Linn. This species, in summer, is 

 found on the elm where it causes a very marked curling of the 

 leaves. Winged individuals in late summer and autumn leave 

 the elm and distribute themselves over a number of different 

 species of plants, amongst which are the currant and goose- 

 berry. The insects infest the roots and are then covered by a 

 woolly material like that of the W T oolly Aphis of the apple. A 



