The Content Of The Article:
- Lifestyle and development
- Affected plants and damage
- Natural enemies
- Preventive measures
- Control of leaf suckers
Leaf fleas (Psylloidea), also called leaf suckers, form a superfamily within the plant lice (Sternorrhyncha). In Central Europe, up to 189 different species of green-yellowish insects are known. The insects reach a size between three and four millimeters. Their hind legged legs allow the leaf suckers to move in excellent jumping - hence they are also referred to as leaf fleas, although they are not related to real fleas. Despite well-developed, transparent wings fly only a few species. The appearance of the animals is strongly reminiscent of aphids or cicadas.
Like other plant lice, but also honeydew honeydew. The sugary secretion attracts ants, flies and bees. Both mature leaf suckers and the larvae produce so-called wax excretions, which should protect the animals from drying out and from the moisture of their own honeydew.
Lifestyle and development
The adult leaf fleas and their juveniles feed mainly on the sap of the infested plants. Therefore, the animals are also called phytophagous phloem suckers. Most leaf fleas are specialized in certain host plants - especially larvae of many species are very demanding in plant selection. However, there are also leaf fleas that infest several related host plants. Some leaf suckers even have a very wide food spectrum and are not picky when choosing plants.
Leaf fleas multiply in two sexes. The females lay their eggs predominantly free on leaves, shoots and stems. Overall, the larvae - so-called nymphs - go through five stages before they skin the adult insect. In Central Europe, most species produce one generation, but there are also leaf-sucking species that make up several generations each year. However, these are mainly found in warmer regions.
Adult leafflies hibernate either on their host plants or on other plants that provide sufficient protection in bark crevices. Im looking for their host plants to lay off the fertilized eggs after mating. Some species also hibernate at the egg stage or as a young on the host plant. After laying the eggs, the first larvae hatch at the end of March. The animals are predominantly found in windless and damp conditions.
Affected plants and damage
Most commonly, fruit trees such as apple and pear are infested with leaf fleas. But ornamental shrubs such as boxwood or hawthorn are among the host plants of insects. Leaf suckers on fruit trees often sting the buds, whereupon the flowers fall off. The boxwood leaf flea (see large photo above) sucks on the shoot tips.
Most leaf suckers damage the plants by sucking on young shoots, leaves and petioles. Other species, on the other hand, prefer the woody branches or roots of the plants. The largest damage to the plants to the larvae. The plants affected by leaf suckers initially show brown and deformed leaves. These are often spoon-shaped bent upwards. Depending on the extent, the fruits of the trees can also be damaged. Most of the small insects are found at the instinctual ends, which begin to wither in a strong infestation.
The larvae of the Great Pear Leaf Sucker infest the flower buds as well as the leaf midribs and the young shoots of the pears. The winged adult animals, however, do little damage
By piercing the plants with the proboscis, malformations or bile-like tissue changes can occur. The sugary honeydew of the leaf fleas also sticks the leaves and sometimes whole branches. It is also a breeding ground for blacktop fungi (Capnodiaceae), which cover it with a black coating. The fungus often causes secondary damage to the affected plants. Especially in pears, this phenomenon is observed more frequently. In addition, leaf fleas and aphids transmit various bacterial and viral infections - which is why they are particularly feared in orchards, because these plant diseases are usually incurable and in many cases result in the loss of the entire plant. One of the most common diseases that infects fruit trees with leaf suckers is fire blight and pear decay.
The most widespread flies in the garden and in agriculture are the apple leaf flea (Cacopsylla mali), the large pear leaf sucker (Cacopsylla pyrisuga), the carrot leaf flea (Trioza apicalis) and the already mentioned boxwood leaf flea.
By promoting natural predators like the ladybug, you can make sure that the leaf suckers in your garden do not get out of hand
The natural enemies of the leaf suckers are among other things spiders, soft bugs, flower bugs and sickle bugs. But the ladybug, gall bladder and parasitic hymenoptera such as parasitic wasps are important enemies of the leaf fleas. In addition, the fungus Entomophthora sphaeroperma decimates the leaf flea populations.
In order to take precautionary measures against leaf fleas, you should promote the natural enemies. Numerous beneficial insects such as spiders, parasitic wasps and lacewings keep the leaf suckers in check.
Through a wintry trunk painting leaf suckers have no way to hibernate on the trees. Where the yellow eggs are visibly attached to the stem, you can easily remove them with a brush.
Fruit sprays and ornamental shrubs can also be protected against pest infestation by winter spraying. The oil-containing preparations stifle the eggs of the leaf suckers reliable, but often harm the beneficials and should therefore not be used too often.
Control of leaf suckers
If you notice an infestation with leaf fleas on your plants, you should act immediately. First remove all affected leaves and shoots. The boxwood leaf flea can be easily removed by hand on the affected plants.
In severe infestation, the use of suitable agents such as pyrethrins ("spruzite") against the sucking insects may be useful. The ready-to-use preparations are available in well-stocked garden shops and on the Internet.