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

In a nutshell

  • Rose beetle larvae are 4 to 5 cm long, c-shaped, have three stunted pairs of sternums
  • The body is white-grey, lateral dots, hairs and head capsule are brown
  • They live in the ground, usually in compost, until they pupate after about 2-3 years
  • They feed on dead plant material and are not dangerous to living plants
  • Control and prevention are not necessary, simply bury again after discovery

The kind of beetle in the garden

If the beetle has made its way into your garden, sooner or later you will come across its larvae. The rose chafers are a huge subfamily of leaf chafers. In this country, however, the common rose chafer dominates, also known as the golden rose chafer. From April to October it flutters through the air, preferably on warm days and around midday. 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 about 14 to 20 mm
  • the upper side is golden green and shiny
  • the underside is colored copper-red
common rose chafer, Cetonia aurata

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

Notice: The Endangered Species Act prohibits killing rose beetles. If you suffer from a large crowd in your garden, you can collect some specimens early in the morning when they are less mobile and release them further afield into the wild.

Appearance of the rose chafer larvae

These are the typical characteristics by which you can recognize a rose chafer larva:

  • Body length reaches 4-5 cm
  • stocky build with lots of brown hairs
  • white coloring with a gray tinge
  • the front end is slimmer than the rear end
  • red-brown, small dots on the sides
  • brown head capsule
  • three poorly developed and short pairs of sternums
  • Larva is curved (c-shaped)
grub of the rose chafer. Source: Fritz Geller-Grimm, Scara fg03, cut from Plantopedia, CC BY-SA 3.0

The beetles lay their eggs

The animals of this species of beetles 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 later the larvae will not be far away either. The eggs are often laid in compost heaps. Moldy tree stumps are also a popular storage place, but rarely found in a well-kept garden.

Notice: The larvae of the rose chafer are often referred to as worms or maggots. However, the scientifically correct name is Engerlinge.

Development of the rose chafer larvae

After a few weeks, the first larvae hatch from the laid eggs. You have a long life ahead of you. Because it takes about two to three years for a larva to pupate again and become a beetle. During this period of time, it grows longer and thicker, so it has to shed its skin several times. In this way we can encounter both small and "adult" rose beetle larvae.

Compost as a typical residence

After hatching, the maggots remain in place, merely moving within the compost heap. Since they shy away from the light on the earth's surface, they remain invisible to us for a long time. We usually encounter them when we rearrange the compost or remove some of it. Due to their white color and their size, they clearly stand out 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 finally moving to the visible part of the garden.

Tip: You can easily recognize a pupated rose chafer larva by the appearance of the cocoon. It is ovoid, about 2 cm long and 1 cm wide. Around it is a thin shell of sand, earth and small pieces of wood.

Beneficial or pest?

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

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

From a purely ecological point of view, there is no reason to fight rose beetle larvae. It also makes little sense to prevent further specimens from hatching. The population of this beetle species usually keeps itself within limits anyway.

What to do after finding larvae?

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

Rose chafer grubs

Maggots in flower pots and beds

Rose beetle larvae can also appear when digging up garden beds or repotting flowers. They probably got there as eggs or pupae, for example when fertilizing with compost. Once you've positively identified them, you should bury them in the compost heap, where plenty of dead plant matter awaits.

Tip: Mature compost should always be sieved before spreading it in the garden. This makes it easy to spot grubs and return them to the compost heap.

Risk of confusion with other beetle larvae

May beetles and June beetles, which also come from the scarab beetles, have similar-looking larvae. If you place the found specimen on a smooth surface and observe it, you will quickly spot the difference based on its movements: the rose beetle larva stretches and crawls away like a caterpillar. She is on her back with her legs stretched out. May beetle and June beetle larvae move hunched and prone.

frequently asked Questions

Do these maggots also eat live plants?

Only in the event that the rose beetle larvae find no more dead material in the garden will they be forced to satisfy their hunger with living roots. In practice, therefore, as good as never!

A larva found in the compost does not appear to be a rose chafer larva. What can it be?

It may be the rhinoceros beetle larva, which also likes to live in the compost and is one of the beneficial insects.

Are all scarab beetle species and their larvae useful?

No. While the rose beetle and rhinoceros beetle are among the useful scarab beetles, the May beetle and June beetle are proven pests that can develop into a plague in some years and cause great damage.

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