Found grubs in your compost heap? Congratulations! Because the grub species that make themselves comfortable there are of the useful kind. So you don't need to worry, you can count yourself lucky.
Grubs drive the rotting process in the compost heap
Differentiation of grub species
The relatively similar-looking larvae of scarab beetles, zoologically Scarabaeuoidea, are referred to as grubs. The best-known and most common representatives of this superfamily in our latitudes are:
- cockchafer
- June beetle
- rose chafer
- garden beetle
- rhino beetle
Typical of grubs are their thick, fleshy caterpillar appearance with more or less long legs in the head area. Depending on the species, they can grow up to 10 centimeters long. Larvae live for a long time, at least 2 years, before they pupate and become beetles.
At times, grubs are generally classified as pests. Some of them are anything but that: they are actually extremely useful and therefore to be welcomed by every hobby gardener. So, being able to distinguish between the species is crucial to being able to benefit from them.
Useful grubs
The useful species are in particular the grubs of the rhinoceros beetle and the rose chafer. Why? Because they do not feed on the roots of living plants like the other species found in our country. They conveniently prefer dead plant material, especially wood. That's why you only find them on compost heaps. When digesting eaten, rotting tree and shrub clippings, these grubs produce humic substances, which, as humus components that only decompose very slowly, lead to the formation of permanent humus. Such permanent humus is very valuable for a gradual, nutrient-rich long-term fertilization of your plants.
How to recognize rhinoceros beetle and rose chafer grubs?
Aside from being identified simply by their presence in the compost, rhinoceros beetle and rose chafer grubs are also directly identifiable by their appearance.
The rhinoceros beetle larvae, for example, are particularly large: they can reach up to 10 centimeters, which is why they are also very easily visible in the compost heap. In contrast to the other grub species, they lack the so-called row of spines in the rear, silvery-grey area. Rose beetle larvae are significantly smaller, only about 3 centimeters long, but very thick-fleshed. They get a little thinner towards the abdomen and have very short legs in front. Their way of moving on their backs is also characteristic.