Yellow-headed Onion Miner

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

The onion miner is found almost everywhere in Russia. It is especially widespread in the south of the European part and in the middle zone of the country. And it harms mainly onions. Gluttonous larvae mine leaves - on their entire surface you can observe numerous mines in the form of short stripes or rounded specks of white color. The harmful activity of these yellow-headed parasites leads to yellowing of the affected leaves and to a significant decrease in the yield of onions

Meet the pest

The onion miner is a rather small insect: the length of its body is only from 1.7 to 2.5 mm. The heads of these pests, as well as the thighs with shoulders, are yellowish, and the abdomens, scutes and mesonotum are blackish with a slight grayish bloom. Legs and tibiae of onion miners are brownish. However, the color of their legs can vary - individuals with little black thighs are often found. Antennae of voracious parasites are usually yellowish, and their last segments are slightly curved from above and endowed with sharply protruding angles in front. All females are equipped with telescopic ovipositor, involved at rest in somewhat elongated tergites 7. By the way, these tergites are often mistaken for the ovipositor themselves.

The size of the eggs of onion miners reaches 0.3 - 0.4 mm. All of them are characterized by an oblong shape and are painted in pearlescent white tones. The larvae can be either yellowish or white. On the posterior tips of their bodies, six cone-shaped processes can be observed, two of which are especially pronounced and reach a length of 4 - 5 mm. And the pseudococoons, the size of which ranges from 2.5 to 3 mm, are colored dark yellow.

Pupae overwinter in puparia in the soil. The appearance of pests on onion plantings can be observed in the first and second decades of May. Moreover, their years are somewhat stretched in time and can last up to two to three weeks. Females need additional nutrition - piercing the leaves on last year's sprouted bulbs with the help of ovipositor, they feed on the juice flowing from them.

The female lays eggs, again piercing the leaves in the upper third with the ovipositor. At the same time, speckled specks located in a row are clearly visible on the tops of the leaves. The eggs are always laid by the females one by one and are attached by them to the inner sheet walls.

After about three days, and sometimes even after five, larvae hatch from the eggs and begin to feed, eating up leaf parenchyma and at the same time forming numerous mines of characteristic shapes and sizes. The development of larvae takes from ten to fifteen days, and during this time they go through three centuries of their development. Larvae that have reached older instars pupate either in the base of the leaves, or nearby in the upper soil layer (at a depth of two to seven centimeters).

Depending on weather conditions on the territory of Russia, from two to three generations of onion miners can develop per year. Most often, harmful parasites attack the testes and onions. If there are about nine larvae or more for each leaflet, a particularly significant damage to the leaves with their subsequent death can be observed.

How to fight

The main preventive measures against onion miners are deep autumn plowing and the elimination of post-harvest onion residues. Not the last role is assigned to the observance of the rules of crop rotation.

When growing onions of different ages, spatial isolation must be observed between plantings. At least the distance between them should be one hundred meters.

Onion leaves damaged by harmful larvae must be cut off and immediately destroyed. Also, during the summer of onion miners, it is recommended to spray seedlings of onion sets and seed plots with "Chlorophos".