Caterpillar pest in my bonsai. What can I do?

A caterpillar is the larva form of a lepidoptera. They have long and segmented bodies and many pairs of small legs. In their adult life, they give us beautiful images in their colorful butterfly form. When we were kids, many of us had silk caterpillars that we fed with mulberry leaves. If you remember, these little worms devoured the leaves we gave them! Then, imagine the severity of a caterpillar plague in any plantation.

How do I know that my bonsai is facing a caterpillar plague?

The partially or completely nibbled leaves are a symptom that should alert us, as well as the presence of silks between the branches and the young shoots. It is also possible to detect the caterpillar fixed on a branch or on a tender bud. Something that can also help us to detect them is that they leave small black droppings in their path.

How can they attack our bonsai?

Caterpillar pests are very destructive. So they will hardly be accompanied by other pests or secondary infestations.

Most caterpillars feed on leaves but there are different groups that feed in a variety of ways.

There is a group of caterpillars known as borers. We can consider it the most dangerous for bonsai.

These feed on wood, and once the caterpillar is already installed in the tree, it digs cavities and galleries that at the end partially or completely dry the tree. These worms reach a large size. This type of caterpillar mostly affects fruit trees such as apple trees, pear trees and even olive trees. Their attacks are made visible both by the holes and by the traces they leave.

The paradox of caterpillars

With the previous explanations its destructive power has become clear to us, but the caterpillars will also be of great help. How? In their adult phase, when they are butterflies. Their diet, composed of nectar and pollen, make butterflies essential actors of Nature, for the pollination of flowers.

Control of caterpillars

Caterpillars can become a serious problem, with limited effectiveness of chemical pesticides due to their production of protective bristles and their location under the leaves or bark.

In case of large and visible caterpillars, simply by removing them with our own hands or cutting the affected buds, we will avoid complications. When the caterpillars are under the bark, the solution involves removing the affected pieces and spraying with pressurized hot water. With this type of caterpillars, insecticides won’t be very effective since they benefit from the protection of the tree itself. However, in case of borers or miners, syringes with flexible needles can be used to inject the insecticide through the cavities of the galleries.

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