ii4 Commercial Gardening 



be seen. As long as the maggot is present in the fruitlet this hole is 

 blocked up with wet brown frass. The larvae move from one fruitlet 

 to another, and must damage a good many during their period of growth. 

 All manner of plums, gages, and damsons are attacked when cjuite small. 

 The adult Sawfly appears in April and May. The female is shiny black 

 with yellowish-red legs, and iridescent wings, and is rather more than 

 J in. in length. The female lays her eggs in the unopened blossoms. 

 These hatch in a few days, and the young Sawfly larvae force their way 

 into the embryo fruit and feed on the developing kernel. The larva 

 inside the plum can at once be told by the number of its legs, there 

 being six jointed legs and six pairs of prolegs and an anal pair. The 

 colour is creamy white, but some have a pinkish tinge, and when full 

 grown reach J in. in length. When mature they enter the soil and form 

 a cocoon of earth, in which they remain as larvae until the following 

 spring. 



PREVENTION. As this pest usually seems to start on a single tree, it 

 is well to have all infested fruit on the tree hand-picked before the 

 insect has time to spread. The only other time we can deal with it is 

 when the larvae enter the soil. Probably then a good dressing of vaporite 

 worked into the soil would destroy many of the larvae before they had 

 spun their cocoons. (See Vol. I, p. 189.) 



The Leaf-curling' Plum Aphis (Aphis pruni). The curling of Plum 

 leaves by Aphis is often very severe, and causes the leaves to fall pre- 

 maturely. The green Aphides which cause this disease are found pro- 

 tected in the curled leaves, where they produce living young with great 

 rapidity. They are the progeny of a dull plum -coloured mother queen 

 Aphis which hatches out before the buds burst, and which may be found, 

 long before there is any sign of leaf or blossom, seated in the axils of 

 the buds. This fat female produces green living young which curl up 

 the leaves. In June this Aphis becomes winged and leaves the Plum; 

 where it goes to we do not know. It returns to the Plums in autumn 

 and produces a sexual brood, the oviparous females laying eggs in and 

 around the bud cluster, where they remain until the next February or 

 March. 



TREATMENT. Treatment consists of early spraying with soft soap and 

 quassia before the leaves become badly curled. Winter spraying in Feb- 

 ruary with thick lime -and -salt wash will stop many of the ova from 

 hatching out, and would destroy any of the plum -coloured mother queens. 



The Mealy Plum Aphis (Hyalopterus pruni). This Aphis forms a 

 mealy mass under the Plum leaves but does not curl them up. This 

 Mealy Aphis appears on the Plums in June and July. It comes from 

 rushes and reeds, being the same as Hyalopterus arundinis, which feeds 

 on those plants. They form much honey dew, which falls on the fruit 

 and which becomes covered with the black soot fungus, and so ruins 

 the fruit for market. In early autumn this Aphis flies back to the rushes 

 and reeds. 



