Tiny Currant Flower Gall Midge

2024 Author: Gavin MacAdam | [email protected]. Last modified: 2023-12-16 13:38

Currant flower gall midge populates almost the entire territory of Russia. And it harms the plantings of black currant. Buds damaged by pests grow unnaturally, turn orange-black and die pretty quickly. Sometimes they can be painted in a pale yellow color with a slight lilac tint. Only one generation of currant flower gall midges manages to develop per year, but this is more than enough to lose a significant part of the berry harvest

Meet the pest

Currant flower gall midge is a tiny pest: the size of its imago is only 1.6 - 1.7 mm. The abdomens of the gluttonous parasites are colored in yellow-orange tones, and at their tips one can see pointed and rather long ovipositor. Their legs and antennae are also long, and the glassy wings of currant flower gall midges are covered with many thin hairs.

The size of the eggs of harmful parasites reaches 0.2-0.3 mm. All of them are characterized by a spindle-shaped oblong shape. And the orange-black larvae grow in length up to 2 - 3 mm. Initially, they are glassy, then, as they grow, the larvae are painted in whitish tones, and adults already acquire bright and saturated shades. The length of the white dense cocoons that form the larvae is about 2 mm.

Harmful larvae overwinter in the soil in rather dense cocoons. Usually such cocoons are located near currant bushes. Pupation of larvae occurs at the stage of blooming of currant buds, and at the very beginning of budding, imago of pests appear - small and rather active flies. Eggs are laid by females in black currant buds. After three or four days, the emergence of voracious larvae begins, feeding on the contents of tender buds. Up to twenty-six larvae can often be found in one bud. Their meals last for two to three weeks. As a rule, buds damaged by currant flower gall midges begin to fall off en masse as soon as the harmful larvae approach an older age.

The larvae that have completed feeding, together with the falling buds, end up on the ground, after which they go into the soil and form numerous cocoons, in which they will stay until next spring. In some cases, some of the larvae can leave the buds even before they begin to fall off. And some individuals also feed in already fallen buds.

How to fight

In early spring and with the onset of late autumn, the soil under the berry bushes should be carefully dug up. Sections of currant bushes heavily damaged by pests must be systematically cut out and immediately burned. It is advisable to pay special attention to this event in the period from June to September.

If the currant bushes have received sufficiently strong damage, when the buds begin to swell, it is allowed to spray with insecticides. They are usually sprayed not only on currant bushes, but also on the soil located around the bushes. Good helpers in the fight against currant flower gall midges are "Tsvetofos" or "Karbofos" (30%).

To prevent the emergence of adults from the soil in early spring or in autumn, pieces of tar paper are laid out under currant bushes (parchment or film is also quite suitable) and sprinkled with earth or mulched with a humus layer or peat crumb. In this case, the thickness of the mulch layer should be equal to ten centimeters.

And in order to scare off the already released currant flower gall midges, it is recommended to treat the soil under the berry bushes with tobacco dust combined with wood ash or with fluff lime in a 1: 1 ratio. A mixture of sand with naphthalene also helps to achieve a good effect - one part of naphthalene is taken for ten parts of sand. As a rule, about a glass of such a mixture is consumed per bush.