Hoplocampa flava Linnaeus.
Taxonomic placing: Insecta, Holometabola, Hymenoptera, Tenthredinidae.
Common name: Plum sawfly.
Geographical distribution: Mediterranean basin, Western Europe, Baltic States, Eastern Russia to Ural, and the Caucasus.
Morphology: The brown-yellow adult is 4-5 mm in length; its antennae are 9-segmented, yellowish. The wings are transparent with yellow veins. The whitish larvae are 9 to 11 mm long, cylindrical, slightly curved, head brownish or orange white to yellowish-green, with three pairs of thoracic legs and 7 pairs of abdominal prolegs.
Life cycle:The pest usually completes only a single annual generation, although the life-cycle may last longer. In the spring females, which feed on nectar and pollen, place their eggs on the host flowers, each female producing about 60 eggs. The emerging larvae bore into developing fruits, wherein they grow and feed, destroying the stone. Each larva may damage several fruits. The mature larvae drop to the ground and hibernate there during summer and winter, pupating in the following spring.
Economic importance: The pest may reduce plum yield by up to 80%, as all infested fruit drop prematurely. The Japanese plum varieties are more heavily attacked.
Management
Monitoring: Samples of plum flowers should be examined in the spring for oviposition marks. These are pocket-shaped slits about 1.5 mm long in the sepal, which turn brown after a few hours).
Cultural control: Autumn plowing and disking between tree rows are used as preventive measures against the sawfly.
Plant resistance: Some plum varieties are partially resistant to the pest.
Chemical control: Neonicotinoids and organophosphates have been used against the pest, initially after the spring appearance of the adults, and then immediately after blossoming.
References
Koropatyuk, E. E., 1975: Plum cultivar resistance to sawfly. Sadovodstvo, Vinogradarstvo i Vinodelie Moldavii 10: 44-45 (in Russian).
http://www.csalomontraps.com/4listbylatinname/pdffajonkentik/hoplocampasppang08.pdf