{"id":382,"date":"2026-08-18T23:33:40","date_gmt":"2026-08-18T22:33:40","guid":{"rendered":"https:\/\/www.coltivobio.com\/en\/?p=382"},"modified":"2026-08-21T07:23:01","modified_gmt":"2026-08-21T06:23:01","slug":"mealy-plum-aphid","status":"publish","type":"post","link":"https:\/\/www.coltivobio.com\/en\/mealy-plum-aphid\/","title":{"rendered":"Mealy plum aphid (Hyalopterus pruni): identification, damage and control"},"content":{"rendered":"

The mealy plum aphid (Hyalopterus pruni<\/em>), also called the mealy aphid, is a fairly common pest of plum trees. It forms colonies mainly on the undersides of leaves and is easily recognizable by the characteristic whitish waxy secretion that covers the individuals.<\/strong><\/p>\n

\"\ud83d\udcf7\"\u00a0Original field photos<\/strong>
\nThe images in this article are original photographs taken personally during field monitoring and observation activities. The symptoms shown therefore refer to real cases observed directly on crops. This article contains affiliate links. We may earn a commission from qualifying purchases.<\/p>\n

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Colony of mealy plum aphids, with the typical waxy-white coloration due to the presence of wax covering the aphids.<\/figcaption><\/figure>\n

Identification and damage<\/strong><\/h2>\n

The aphids are light green in color, often almost completely hidden by the whitish wax (see photo below). Colonies can become very numerous and affect large portions of the canopy.
\nDirect damage is caused by sap removal<\/strong> and, in more severe infestations, can result in yellowing, reduced growth, and premature leaf drop.
\nIndirect damage is often more evident. The aphid produces abundant honeydew<\/strong>, on which sooty mold<\/strong><\/a> subsequently develops. Leaves and fruits can therefore become covered with a blackish coating that, especially close to harvest, can compromise the commercial quality of the crop.<\/p>\n

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Colony of mealy plum aphids. The production of wax, mixed with honeydew, which has fallen onto the leaf below, can also be seen.<\/figcaption><\/figure>\n

Life cycle<\/strong><\/h2>\n

Hyalopterus pruni<\/em> generally overwinters as an egg on Prunus species<\/strong>. In spring, with the resumption of vegetative growth, the first generations emerge and the colonies increase rapidly.
\nBetween late spring and summer, winged forms appear and migrate mainly to reeds (Phragmites<\/em>)<\/strong>, which are used as secondary hosts. In fall, winged individuals return to Prunus species, where sexual reproduction takes place and overwintering eggs are laid.<\/p>\n

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\n\t\t\tRead also: Plum rust, symptoms and damage\t\t<\/div>\n\t\t\t\t\t\t
\n\t\t\tPlum rust is a fungal disease caused by fungi. It mainly affects the leaves and is generally a mid-to-late season disease, which can become important during the second part of the growing season. \t\t<\/div>\n\t\t\t<\/div>\n<\/div>\n\n

Monitoring and beneficial insects<\/strong><\/h2>\n

Monitoring should begin by observing mainly the undersides of the leaves<\/strong>, trying to identify the first colonies before they produce large amounts of wax and honeydew.
\nBefore treating, it is important to check for the presence of beneficial insects<\/strong>. Ladybugs, hoverfly larvae, lacewings, and Aphidoletes aphidimyza<\/em> are important aphid predators. Several parasitoid wasps also contribute to natural control, leaving the characteristic “mummies” of parasitized aphids on the leaves.
\nWhen beneficial insects are numerous and the infestation remains limited, an insecticide treatment may therefore be unnecessary or even counterproductive.<\/p>\n

Control<\/strong><\/h2>\n

Against initial infestations, azadirachtin<\/strong><\/a> can be used, an active ingredient extracted from neem that interferes with aphid feeding, development, and reproduction. It is generally more useful when applied early, before colonies reach high densities.
\nHorticultural oil<\/strong><\/a> can also contribute to control, mainly due to its contact action. In this case, it is essential to obtain good coverage of the vegetation, particularly the undersides of the leaves.
\nAs an alternative to horticultural oil, insecticidal soap<\/strong><\/a> can also be used.
\nNatural pyrethrum<\/strong><\/a> has a rapid knockdown action and is effective against aphids, but it has the major limitation of being not very selective toward beneficial insects<\/strong>. Its use should therefore be carefully evaluated when ladybugs, hoverflies, lacewings, and other natural enemies are present.
\nThe best strategy therefore remains to treat the first colonies<\/strong>. Unlike the leaf-curling plum aphid (see here)<\/strong><\/a>, this aphid does not curl the leaves and therefore also allows the use of contact insecticides.<\/p>\n

Useful insecticides<\/strong><\/h2>\n