Boxwood Borer Eggs – Early Detection & Removal

Last updated on October 23rd, 2023 at 08:52 pm

boxwood borer is considered the most feared pest of this plant. He is not wary of the poison of the boxwood. The caterpillars eat the leaves and shoots without stopping. Without timely control of the caterpillars, there is a risk that the boxwood will die and not recover.

When the small butterfly lays its eggs on the boxwood, the ominous task of driving the pest away begins. The most effective way to do this is to recognize and eliminate the boxwood borer eggs at an early stage.

But how do you recognize the boxwood borer eggs and how do you remove them effectively?

The voracious caterpillar is an early developmental stage of the box elderworm. The moth first develops from eggs into a caterpillar before it is able to leave the boxwood. The caterpillar is so hungry that an infestation often leads to the complete death of the boxwood.

If the boxwood borer moth finds itself in your garden, it begins to lay eggs. In order for the boxwood borer eggs to grow optimally, they are located on the outer leaves of the boxwood. From there, the larvae pupate and later grow into the caterpillar. Once the caterpillar has eaten enough food, these become the boxwood borer moths and the cycle begins again.

As a gardener, it is important to recognize the boxwood borer eggs to break this cycle. Otherwise, multiple generations per year will grow on your boxwood and leave significant damage in their wake.

Up to four generations per year can grow. This depends on the temperatures. In warmer regions, the boxwood borer moths start laying eggs earlier. In Europe, three generations per year are common.

The eggs are located on the outer edges of the leaves. From there, the caterpillar eats its way inwards to the boxwood and causes a lot of damage. Only by regular control and good care of the boxwood you can detect the boxwood borer eggs early and prevent them from spreading.

The danger of the box tree borer eggs during the year

The boxwood borer goes through various stages of development until it grows into a moth. The exact course of these stages depends on the weather. Therefore, it is difficult to predict at what point in the year the first laying of eggs will occur.

However, you can tell for yourself with simple means, whether the season for the boxwood borer has already begun. To do this, use a boxwood borer trap. You can set it up in the garden and observe whether the moths fall into the trap. If you collect the first butterflies, this is a clear signal that your boxwoods are in danger. For now the moth could be laying its eggs and the boxwood borer caterpillars could be growing.

If the boxwood borer eggs have already developed into caterpillars, these are so resistant that they survive even the winter. In the following year, the caterpillars awaken at warmer temperatures and go through the various stages of development.

Roughly, a yearly overview looks as follows:

April
Overwintered caterpillars feed on boxwood. They still belong to the generation of the previous year.

May
When the caterpillar has eaten its fill, it remains as a cocoon on the boxwood. Initially, no further damage occurs.

June
The boxwood borer moths hatch from the cocoons. Within a very short time, they lay eggs on the boxwood again. The first generation of the year grows up.

July
Caterpillars develop from the eggs. Now the damage to the boxwood is most visible.

August
The caterpillars pupate and remain on the boxwood. Sometimes the first boxwood borer folds appear, which in turn begin to lay eggs. The second generation of the year is haunting your garden.

Recognize the eggs of the boxwood borer.

The period from the recognition of the eggs to the development into a caterpillar is conceivably short. That’s because after the eggs are laid, it takes only three days for the hungry larva to hatch and descend on your boxwood.

So it could be that you go on vacation for only one week and after your arrival the boxwood is marked by heavy infestation of caterpillars.

Therefore, it is even more important that you recognize the eggs early and take appropriate countermeasures. The more carefully you proceed here, the less work you will have later, when the caterpillars hatch from the boxwood borer eggs.

The lifetime of the small butterfly is extremely limited. It lives only about 8 days and during this time it has to mate and lay eggs. A female is able to lay up to 150 eggs.

The eggs are somewhat protected on the underside of the leaf. Preference is given to the outer leaves, as these are easier to reach for the boxwood borer moth.

The eggs can be recognized by their almost transparent consistency. In a subtle yellow, they are only a few millimeters in size. Nevertheless, the eggs can be easily identified when looking closely. This is because on the underside of the leaf are the ice mirrors, which consist of 20 closely spaced eggs.

If black dots can be seen inside the eggs, this indicates that hatching is imminent. The head coils of the larvae can then be seen through the eggs.

Within its young life, the box elder goes through six larval stages. To prevent the larvae from growing into caterpillars, removing the eggs at an early stage is the best defense method against boxwood borers.

Removing the boxwood borer eggs.

Set traps in the garden and check the undersides of boxwood leaves. Then you can prevent a heavy infestation and prevent the voracious caterpillars from spreading. Use the following methods to effectively remove boxwood borer eggs.

Pruning the boxwood

If the first moths have fallen into the trap, the eggs will likely already be on the boxwood. If you have several plants at once and want to keep the effort relatively low, perform a pruning.

Pruning should be done a good two weeks after the moth flight. Then the egg laying has taken place with high probability.

When pruning, remove the outer leaves and shoots. This will ensure that the eggs are no longer on the boxwood and you will not have to examine each underside of the leaves individually.

Natural predators

The eggs are considered an optimal place for some natural predators to lay their eggs themselves. This applies, for example, to the ichneumon wasp.

This wasp likes to search for the boxwood borer eggs in order to lay its own eggs there. This behavior prevents the development of the boxwood borer larva and it dies already in the egg.

It is practical that you can easily purchase the eggs of the hatchling wasp in stores. Spread the eggs in your own garden and the ichneumon wasp will independently go in search of the boxwood borer eggs.

In the garden, however, this approach does not always prove promising. The ichneumon wasps might choose other places and leave the box elder beetle eggs alone as far as possible. More effective is the approach in a protected greenhouse, where the ichneumon flies find few alternatives.

Protect the boxwood with nets

Visually unattractive but effective in the fight against the eggs of the boxwood borer are also nets. The nets are stretched around the box trees between April and September. Thus, the boxwood borers do not gain access and egg laying is impossible.

This method is especially suitable if you take care of a large number of box trees. In a small garden, the nets often look inappropriate and disturb the atmosphere.

The eggs of the boxwood borer

If you want to prevent the infestation of caterpillars of a boxwood borer, you can get to the “root” of the problem right away. By carefully combating the eggs, the caterpillars will not develop and target the leaves.

In small gardens with only a few boxwoods, the most practical approach is to scan the underside of the leaves for eggs. This is the most likely way to detect boxwood borer infestations and manually remove the eggs.

You will also counteract the infestation by selective pruning during the usual egg-laying period. Netting is recommended for the vacation season. Since only a few days pass from egg laying to hatching of the larvae, you protect yourself from a nasty surprise.

By paying special attention to box elder eggs, you will save yourself a lot of work later. Protect your boxwood from the pest and thoroughly deal with the eggs.