Rose chafer larvae: what to do?

Rose beetles are frequent garden visitors. So it is inevitable that they lay their eggs in the ground. The hatched maggots are not a pretty sight, but are they also harmful?

The beetle species in the garden

When the beetle has made its way into your garden, sooner or later you will come across its larvae. The rose beetles are a huge subfamily of leaf beetles. In this country, however, the common rose beetle, also known as the golden rose beetle, predominates. From April to October it flutters through the air, preferably on warm days and at lunchtime. Rose blossoms and umbelliferous plants have done it to him. It is easy to spot and recognize because its appearance is striking:

• Body length is approx. 14 to 20 mm
• the upper side is golden green and shiny
• the lower side is colored copper-red

The damage caused by feeding on the rose beetle is hardly worth mentioning, but its usefulness as a flower pollinator should be emphasized. This valuable contribution to the ecosystem earned him the title "Insect of the Year 2000".

Note: The species protection law forbids that rose beetles are killed. If you suffer from a large number in your yard, you can collect some specimens early in the morning, when they are less agile, and release them further away into the wild.

Appearance of the rose chafer larvae

These are the typical characteristics that you can use to recognize a rose chafer larva:

• Body length reaches 4 to 5 cm
• stocky build with lots of brown hairs
• white tint with a gray tinge
• the front part is slimmer than the rear end
• reddish-brown dots on the sides
• brown head capsule
• three poorly developed and short pairs of sternum bones
• Larva is curved (c-shaped)

Beetles lay their eggs

The animals of this species of beetle lay their eggs in the environment in which they live. If you have already been able to observe the insects in your own garden, their eggs and, subsequently, the larvae will not be far away either. The eggs are often placed in compost heaps. Moldy tree stumps are also a popular storage location, but rarely found in a well-tended garden.

Note: The larvae of the rose beetle are often referred to as worms or maggots. However, the scientifically correct name is grubs.

Development of the rose chafer larvae

After a few weeks, the first larvae hatch from the laid eggs. You still have a long life ahead of you. Because until a larva pupates again and becomes a beetle, it takes about two to three years. During this period of time it becomes longer and thicker and consequently has to shed its skin several times. So we can encounter both small and "fully grown" rose chafer larvae.

Compost as a typical place to stay

After hatching, the maggots remain in place, only move within the Compost heap. Since they shy away from the light on the surface of the earth, they remain invisible to us for a long time. We usually encounter them when we shift the compost or remove some of it. Due to their white color and their size, they clearly settle in the dark-colored compost. But not only hatched grubs can appear. Pupated specimens can also be found in the compost. Even the beetles stay in the compost for a while after hatching before they finally move into the visible part of the garden.

Tip: You can easily recognize a pupated rose chafer larva by the appearance of the cocoon. It is egg-shaped, about 2 cm long and 1 cm wide. Around him is a thin cover made of sand, earth and small pieces of wood.

Beneficial or pest?

After the discovery of rose beetle larvae, is it imperative to think about combating it immediately? Does early prevention even make sense? We get a clear answer if we take a look at their eating behavior:

• Larvae only eat dead plant remains
• the excretions are useful for the formation of humus

From a purely ecological point of view, there are no reasons to control rose chafer larvae. Nor does it make sense to prevent further specimens from hatching. The population of this beetle species is usually limited by itself.

What to do after larvae are discovered

Since the maggots, Egerlingen, worms or whatever you like to call them personally do not pose a threat to living plants, they - resp. in fact, because of their usefulness, they should - stay alive. However, unearthed on the light-filled surface, they are not in good hands. They are not used to the sun and must quickly disappear into the earth, otherwise they will dry out. Help them! Put the blooms back on the compost heap and cover them with a few inches of soil.

Maggots in flower pots and beds

When digging up garden beds or repotting flowers, rose chafer larvae can also appear. They probably got there as eggs or pupae, for example when fertilizing with compost. Once you've clearly identified them, you should bury them in the compost heap, where there is plenty of dead plant material waiting for them.

Tip: You should always sift mature compost before distributing it in the garden. This makes it easy for you to spot grubs and put them back on the compost heap.

Risk of confusion with other beetle larvae

Cockchafer and June beetle, which also come from scarab beetles, have similar looking larvae. If you place the found specimen on a smooth surface and observe it, you will be based on the Movements quickly make the difference: The rose beetle larva stretches and crawls like a caterpillar of that. She is on her back with her legs sticking up. May and June beetle larvae move curved and lying on their stomach.

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