Garden leaf beetles are not always accepted because their larvae, which live in the soil, are not welcomed by hobby gardeners. But insects are rarely considered pests. If they become a nuisance, special measures must be taken.
How to control garden beetles?
Garden beetles usually do not cause much damage. If there is an infestation, nematodes or pheromone traps can be used to control it. Chemical control agents should be avoided as they can also affect beneficial insects and cause environmental damage.
Garden leaf beetle in the garden
Usually there is no need to worry if you discover a garden beetle in the garden. The insects feel particularly comfortable there because they find a rich supply of food. The animals generally do not cause any damage. Even if the approximately 15 millimeter large larvae appear in large masses, they do not cause any significant damage.
Only in exceptional cases do garden beetles cause major damage to lawns or roses.
malicious image
If gaps and patchy brown discoloration appear in the lawn, grubs are often the cause. Garden leaf beetle damage can occur between July and September. Birds peck the grubs out of the loose soil, causing the lawn to be further torn up. The eaten grasses can no longer establish themselves and show stunted growth.
If grubs appear in large numbers, the turf can become loose, with such severe damage being caused by other scarab beetle larvae. In isolated years the adult beetles can be observed en masse on roses. They leave traces of feeding in flowers and petals, although the damage is not significantly high.
The garden leaf beetle causes great damage
What to do about garden leaf beetles?
If the garden beetle has caused damage to the lawn, you should prevent further reproduction. There are effective remedies you can use to combat the plague. However, all measures also have disadvantages that you should assess beforehand.
Tip
You should identify the grub before taking control measures. They can also be useful species that do not harm your lawn.
Poison
Chemical control of garden leaf beetles should be avoided, as sprays not only affect pests but also beneficial insects. Chemical agents are usually ineffective against flying insects. If the soil is treated with poisons, toxic substances can enter the groundwater or have negative effects in nearby surface waters.
Nematodes
Nematodes are an effective way to combat grubs in the soil. The species Heterorhabditis bacteriophora is parasitic and uses the larvae of the garden chafer beetle as a host. They penetrate the body openings and secrete a bacterium that causes the organisms to die within a few days.
Application of nematodes:
- between July and September
- Soil temperature of at least twelve degrees Celsius
- Mix powder with water
- water on the lawn within 45 minutes
- Only apply on cloudy days due to high UV sensitivity
Fight naturally
Natural control of potential pests is always better than chemical treatment. The impact on the environment and he alth is as low as possible and the beetles are reduced in a gentle way.
Tip
Many insects do not like the smell of garlic. Place some plants directly on the lawn or stick garlic cloves in the ground.
Attractant
Special funnel traps attract the animals using pheromones. Extracts from natural plant fragrances are used as attractants. Such traps are set during the flight season between May and July. Since the beetles only fly in dry weather from morning to early afternoon, the trap cannot be used to reduce the population. Such pheromone traps are primarily used to record the appearance of the species.
These substances are attractive to garden beetles:
- Hexanol: leaf alcohol
- Eugenol: component of clove oil
- Geranio: component of rose and geranium oil
Excursus
How pheromone traps work
Garden leaf beetles fly at a height of between 50 and 100 centimeters during their swarming flight, which is why the attractant trap must also be installed at this height. The traps release attractants via a dispenser that attract both male and female beetles. It turns out that garden beetles are more often attracted to yellow surfaces. The color yellow, in combination with the fragrances, looks like a flower that the beetles fly towards. They fly into vertically arranged impact surfaces and fall into a funnel.
Build your own trap
For a homemade trap you will need a dark green plastic pot and two yellow plastic plates. Alternatively, you can use a plexiglass pane that you saw into two parts and cover with yellow foil. The two pieces are later put together so that they form a cross. To do this, you must saw a notch in both sections - starting from the shorter edge - up to the middle of the panels. The cross is placed in the pot and now forms eight baffles.
- Stick the bottle with attractant on the cross
- Place the trap at a height of 50 to 100 centimeters
- check daily
Profile
The garden leaf beetle (Phyllopertha horticola) belongs to the scarab beetle family and is incorrectly called the June beetle. The beetles are around eight to eleven millimeters long and can be recognized by their light brown colored wing coverts. The rest of the body is densely hairy and shines a metallic black-green. The fine granulation of the body and the rows of dots on the elytra are striking. Garden leaf beetles have short antennae that end in a three-lobed fan.
Difference between garden leaf beetle and cockchafer
Cockchafers reach a body size of between two and three centimeters and are therefore significantly larger than garden leaf beetles. They have a shiny black body that is hairless. The compartments also differ between species. In cockchafers, the antenna ends in six to seven lamellae.
Difference between garden leaf beetle and June beetle
Various species from the genera Amphimallon and Rhizotrogus are often referred to as June beetles. This common name is common for the ribbed curlew beetle. More rarely, the garden leaf beetle is also referred to as the June beetle. They all belong to the scarab beetle family.
| Scientific name | Coloring | Hair | |
|---|---|---|---|
| Ribbed Curlew Beetle | Amphimallon solstitiale | leather yellow to brown | side eyelash bristles |
| June beetle | Rhizotrogus marginipes | variable shades of brown | fitting |
| Garden leaf beetle | Phyllopertha horticola | black-green body, light brown wings | tight |
Occurrences
Garden leaf beetles are found in Europe and Asia. Their distribution area extends into central Fennoscandia. In the south of Europe, the mountainous regions limit the area. The beetles inhabit fields and meadows, with forest edges and hedgerows being preferred habitats. Garden leaf beetles are also found in gardens. They can be found from the lowlands to the mountains and are a widespread and common species in Central Europe.
Lifestyle and development
The species is diurnal and flies from May to July in search of food and partners willing to mate. One generation is created each year and remains in the ground at least until next spring. In suboptimal conditions, larval development can extend over two years.
Mating season is from May to July
Larval development
Females lay up to 40 eggs, preferring loose and sandy soil in sunny places as a place to lay their eggs. It takes about five to six weeks for a larva to hatch from the egg. The grubs live in the ground and go through three larval stages before pupating. In order to survive the winter unscathed, the larvae retreat to deeper, frost-free layers of soil. They pupate next spring and hatch after about three weeks. Adult beetles have a life expectancy of about four weeks.
Food
The beetles' diet includes leaves from various deciduous trees. They prefer the foliage of birch, oak and hazelnut bushes. Occasionally they also eat flowers, with cherry tree and rose blossoms being particularly popular. The larvae, which live in the soil, feed on plant roots, especially those of grasses, until they pupate.
Grub grub menu:
- first stage: small humus particles
- second stage: roots of fine grass species
- third stage: all plant roots
Natural enemies
All insectivores can be dangerous to the garden leaf beetle. Its natural predators include a number of mammals such as shrews, bats, moles and cats. There are also numerous birds that hunt the small beetles.
Frequently asked questions
What does the garden leaf beetle look like?
The garden leaf beetle is densely hairy all over its body. Except for the light brown wing coverts, the beetle is black-green in color and has a metallic shine. Its antennae are striking because they end in a three-lobed fan. Black dots can be seen on the wings, arranged in six rows per elytra.
How old does a garden leaf beetle get?
The development from egg to adult beetle takes a long time. Normally, the newly hatched larvae live in the ground overwintering until the next spring and then pupate. Sometimes this development takes two years. The adult beetles live up to four weeks.
Which home remedies help against garden leaf beetles?
Put plants in your garden that are poisonous to the grubs. Geraniums and delphiniums have emerged as an effective way to control the larvae. Only the third instar larvae eat the thicker roots. To prevent females from laying eggs, you can plant garlic.
How can I prevent a garden leaf beetle infestation?
The beetles prefer loose sandy soil in a sunny location as a place to lay their eggs so that their larvae develop optimally in the soil. A patchy lawn promotes egg laying because then the females can lay their eggs directly on the ground. Make sure that the lawn has extensive vegetation. If you notice an infestation, nematodes or thoroughly loosening the soil will help. The grubs need moisture and will die within a short time if the substrate is ventilated.
