Minibeasts - Why are Minibeasts Important?

Some people regard most ‘creepy crawlies’ simply as pests, in need of extermination! Indeed some of them can be pests to us humans, spreading diseases and eating our crops, but in fact, all invertebrates are a very important part of life in the habitat in which they live. We will take a woodland as an example.

Invertebrates are found in all layers, from the floor to the canopy (branches and leaves of the trees) and they are a very important source of food for several mammals and birds. Some birds feed only on insects and most seed-eating birds feed their babies on insects. Hundreds of different butterflies and moths lay eggs on the leaves of the trees. When the caterpillars hatch they feed in huge numbers on the leaves. During the summer, a large oak tree can support 400,000 caterpillars at any one time! If all these caterpillars survived, then the trees would be stripped bare of leaves. Before this happens, the population of small woodland birds usually increases and many of the caterpillars are eaten.

Many other invertebrates live amongst the canopy; wasps, flies beetles, weevils and bugs such as aphids, may all be found there. The larvae of some of these tunnel into leaves as they feed whilst others produce swellings or ‘galls’ on the leaf buds, flower buds or leaf surface. These herbivorous minibeasts are preyed on by carnivorous minibeasts such as ladybirds, lacewings, ants, mites and bush crickets. Small birds will eat most of these invertebrates.

Some beetle larvae have strong jaws so they can munch their way through the wood of a tree trunk, making a network of tunnels as they feed. These wood-boring beetles are hunted by woodpeckers, such as the great spotted woodpecker, which drills beneath the bark with its powerful beak to find them.

The leaf litter and soil of the woodland floor provide homes for thousands of minibeasts. Others live in and under rotting logs. Slugs, snails, earthworms, millipedes, mites, springtails, woodlice, ants, beetles and fly larvae all feed on dead leaves which fall from the trees. These invertebrates are hunted by the carnivorous beetles, centipedes, spiders and harvestmen.

Many of the minibeasts which live in leaf litter are classed as decomposers and they have a very important job to do in an ecosystem. As well as feeding on dead leaves, some of them also eat dead trees and the droppings and dead bodies of animals. In fact, any waste plant and animal material is eaten. All waste material still contains nutrients. The minibeasts break the material into tiny bits and use some of the nutrients in them for themselves. The fragments left are then easier for microscopic worms, fungi and bacteria to feed on and break down even more, releasing nutrients into the soil. The plants soon absorb these nutrients, and so the cycle continues. If the decomposers did not exist, then nothing would rot down and we would be surrounded by piles of dead bodies! Next time you try to swat a fly, remember that although it may be a nuisance to you, it is also one of nature’s recyclers’!