The chirping song of the cicadas often belies the fact that these insects do not belong to the grasshoppers, but rather are closely related to the bed bugs. The brightly colored animals are pests and in rare cases can cause damage to the host plants through their ingestion. But don’t panic if you spot the winged insects on your own plants in the garden. Control is only necessary in rare cases.
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Occurrence and damage
The animals, which are often only a few millimeters in size, are easy to see with the naked eye and prefer to stay on the underside of the leaf of the infected plant. By sucking and pricking, cicadas extract the valuable cell sap from the plants with the help of their mouthparts. Silver-colored to white-yellow speckles on the leaves are the first visible signs of an infestation. An effect caused by air that has penetrated the inside of the plant through the suction holes. Rolled-up shoot tips and dried up leaves appear as soon as the population of the insects – and with it their food consumption – increases. Before you take effective countermeasures, however, you should first play it safe. Because other sucking pests, such as spider mites and aphids,
Cicadas are extremely happy to jump and prove this when there is danger. Depending on the type of cicada, you can also find other traces on the plants: A foam-like structure on the stems and leaves of the plants is a sign of foam cicadas. This substance – also called cuckoo’s saliva – protects the newly hatched cicada larvae from potential predators in spring. The material, caused by the droppings of the cicadas offspring, does not secrete any harmful substances to the plants. In Central Europe, well over 35 species of the leafhopper are known, the meadow leafhopper is most common in home gardens.
Another frequently encountered cicada species prefers rhododendron varieties, from which the name “rhododendron cicada” is derived. While leafhoppers rarely cause significant damage to the host plants, the situation is different for family members who love rhododendrons. Here, too, the cicadas feed on the cell sap of the plants and cause discoloration and speckles on the leaves. The actual damage does not begin until the eggs are laid in autumn, when the insects poke small holes in the buds of the rhododendron. Because the inside of the buds not only offers protection to the animals’ eggs, but is also the basis of food for the fungal pathogen Pycnostysanus azaleae. The so-called “bud tan” is a visible indication of a fungal attack.
From predators and other biological agents
Depending on the body size and the strength of the population, cicadas often go undetected in the home garden. Damage caused is often only a visual disturbance and does not reduce the budding or growth of the plant. The fight against flying insects is lengthy, but by no means complicated. When choosing effective control measures, the respective species of cicada plays an important role.
Foam leaf hoppers can be washed away in spring with a sharp jet of water on plants with strong shoots. Repeat this process several times to remove all larvae from the plant. Or you can carefully apply a solution of neem oil to the infected parts of the plant. This process must also be carried out several times in a row in order to bring all insects into contact with the agent. In order to prevent the adult animals from laying eggs, yellow boards or yellow stickers can be placed in the immediate vicinity of the host plant. If necessary, replace the sticky traps to capture any adult cicadas.
However, you don’t always have to resort to home remedies when fighting the strikingly colored insects. Because cicadas are also viewed as a nutritious meal by some other animal species. The natural predators of the auchenorrhyncha include, for example:
- Predatory bugs
- be crazy
- Ants
- Birds
- Grabwespen
If you rely on animal support in the fight against the cicadas, the ideal environment must be created around the infested plants. For example, you can use sugar water to attract ants in a targeted manner or collect spiders from other parts of the garden to expose them to the pests in the immediate vicinity. Cicadas are extremely sensitive to changes in location and changes in the soil. The animals are considered bio-indicators and are a sign of an intact and healthy garden structure. If there is no visible damage to the host plants, you should therefore refrain from using neem oil and yellow stickers.
Effectively remove rhododendron cicadas
Adult cicadas are often carriers of numerous parasites and fungal spores. The latter also includes Pycnostysanus azalea, which causes the feared bud tan in some rhododendron species. Effective fungicides against the fungus are not available on the market. You will therefore have to resort to other methods to rid the ornamental plants. The first option would be to prevent the insects from laying eggs directly. Rhododendron cicadas are also attracted by the color yellow, apply yellow stickers close to the infested plants. Diluted vinegar essence or neem oil have also proven effective, but the treatment must be carried out continuously and regularly. Check daily whether the leafhoppers are reacting to the remedies or whether damage is being done to the plants instead.
Check the rhododendron in spring and remove any black or brown buds without leaving any residue. In order to prevent the fungal pathogen from spreading again, the plant parts must not be added to the compost, but are instead disposed of with household waste. Cicadas are extremely nimble and often it is not possible to completely eliminate all animals from the host plant. If the fungal infestation persists, then resort to insecticides. The larvae of the insects are mainly fought with chemical means, the ideal time for this is in June. Apply the chemical product carefully and avoid contact with crops intended for consumption.
Useful tips and tricks
Over 50% of the cicada species occurring in Germany are threatened with extinction and are on the list of endangered animal species. Instead of taking countermeasures against the fascinating animals, you can also take preventive measures against an infestation.
- During planting, a sufficiently large minimum distance between the individual plants should be ensured. This not only ensures that the plants have enough space to develop, but you can also control pest infestation in a more targeted manner and curb its spread.
- A brew of nettles or field horsetail works in many ways against harmful insects. Mix part of the brew with the irrigation water and give it to the plants regularly. There should be no direct contact with the undiluted liquid, as sensitive plants react to it with burns. Use the following recipe for the brew:
- 1 kilo of fresh or 150g of dried leaves
- 10 liters of boiling water
Pour over the nettle or horsetail leaves and let them steep for about 2 to 3 days. If necessary, prepare a new broth, the remains of the leaves can be used as nitrogen-rich fertilizer.
Resistant hybrids
If you are looking to buy new rhododendrons for the garden, you should resort to resistant varieties. Specially bred species are not attacked by the colorful cicadas or the notorious bud tan. The following rhododendron varieties are extremely resistant to pests from North America:
- Repens
- Yakushimanum
- Williamsianum
You can therefore enjoy the lush flowers of the ornamental plants every year without having to accept losses from cicadas or fungal pathogens.
Cutting
The offspring of the rhododendron cicadas overwinters in the infected plant buds. In late autumn, cut back the plants and dispose of the clippings with normal household waste. Compensate for the loss of branches in spring with nitrogen-rich fertilizer, which stimulates the plant to form new buds and shoots.
Conclusion
Cicadas are extremely fascinating and often strikingly colored insects that feed on the cell sap of the plants. Only in a few exceptional situations – such as an infestation with rhododendron cicadas – do you have to take active action against the insects that are capable of flying and jumping. The fight is carried out with common means, but the visible success is only achieved after some time. Patience and perseverance are therefore essential in successfully eliminating the cicadas.
