Fight green caterpillars in the boxwood

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Fight green caterpillars in the boxwood: green

Green caterpillars populate a boxwood, sounding alarm bells from experienced hobby gardeners. They are confronted with the boxwood beggars imported from East Asia, which destroyed huge boxwood stocks within a few years. The green caterpillars are the gluttonous brood that the small butterfly lays in the bushes. As they pass through several larval stages, they mercilessly eat leaves and shoots until the plant dies. To combat the voracious pests, various methods have emerged in the meantime. About the exact procedure clarify the following lines.

way of life

Effective combat requires the exact knowledge of the life of a boxwood turkey, because he has developed a clever technique that keeps the green caterpillars secret for as long as possible. The toenailer is a small butterfly with cream-colored wings bordered with brown. With a wingspan of 4.5 centimeters, it is easy to see. During their short lifetime of 10 days, the female butterflies stealthily never spend a long time on a boxwood, but fly it only to lay eggs inside the shrub. In March, the first generation of caterpillars hatch. These are 5 inches long when fully grown and have a green body with black stripes. So the infestation takes its course:
  • The caterpillars eat the leaves and shoots in the lower shrub area
  • Gradually, the pests work their way outward
  • To protect against cold they form bright webs
  • During the year, up to 4 generations develop
  • The last generation overwinters in the gray cocoons
At the end of the attacked boxwood is eaten bald except for the skeleton and wrapped in gray or light beige webs, reminiscent of spider webs. Under the boxwood brown or green Kotkrümel can be seen, as a further indication of the presence of the caterpillars.
Tip: When buying a boxwood, look carefully for the grayish cocoons to avoid picking up any contaminated plant.

Mechanical combat

If the infestation is at an early stage, good results are achieved by the use of mechanical control techniques. This requires that you periodically inspect your box trees for clues such as gray spots, eaten leaves, or droppings.


Environmentally conscious hobby gardeners take this natural method to combat green caterpillars in the boxwood. Armed with tweezers, locate the usually nimble escapes, especially in the early morning hours, when they remain cold-frozen in the bush.

high pressure cleaner

If several generations of the green-colored larvae have already developed, you will hardly succeed in collecting. In this case, the sharp jet of water from the pressure washer eliminates the pest. Here's how to do it:
  • Spread a foil under the boxwood that reaches up to the root collar
  • Spray the shrub with the water jet of the high-pressure cleaner at the highest possible level
  • Start in the crown and continue down
  • Focus on the inside of the boxwood
Experienced hobby gardeners play it safe by repeatedly repeating the process throughout the day.

light trap

Boxwood - Buxus

The measures to contain and eliminate the plague are intensified by the use of light traps. Since the adult butterflies are nocturnal, they are attracted with light in the ultraviolet range and captured by adhesive boards. In a radius of 10 to 15 meters you prevent in this way, at least in part, the further oviposition. In addition, this method provides information on the extent of infestation based on the number of captured specimens.

Biological methods

In order to successfully combat green caterpillars in boxwood, the handling of chemical preparations is not absolutely necessary. If the mechanical techniques fail, because of the high amount of pests, biological control methods are the next step. These score with the advantage of a beneficial nature-friendly procedure. The following alternatives have proven themselves:

Bacillus thuringiensis

This naturally occurring bacterium has become established worldwide in responsible pest control. Since it acts specifically on the green caterpillars, neither plants, nor vertebrates or even humans come to harm. How to apply the preparation:
  • From a constant temperature of 15 degrees Celsius and higher applicable
  • Apply the liquid with a pressure sprayer
  • Spray again after a waiting period of 10 days
The biological preparation acts as a feeding poison, so the caterpillars have to absorb it. As soon as this happens, a direct feeding stop begins.A few days later the butterfly caterpillars have died.

neem oil

In its Asian homelands, the boxwood farmer has been at work for decades. The local gardeners report good successes in the fight against the green caterpillars with neem oil preparations. Obtained from the seeds of Indian neem tree, the oil contains a natural insecticide that has lethal effects on pests. How to apply it:
  • For the preparation as a spray add 1 liter of water to 5 ml of neem oil
  • The emulsifier for the oil-water compound is 1.5 ml of Rimulgan
  • Filled in a spray gun or a pressure sprayer, distribute the agent into the bush interior
When temperatures drop below 7 degrees Celsius, neither biological nor chemical insecticides will work against the boxwood creamer and the green caterpillars. The pests retreat into impenetrable cocoons to overwinter.
Tip: Position several yellow sheets in the immediate vicinity of your box trees. With the aid of these sticky traps, you can quickly determine if the boxwood borer is present in the garden.

Beneficiaries avoid the green caterpillars

As part of close observation, scientists have discovered that the beneficials of the garden avoid the green caterpillars of the boxwood conifer. What works excellently in other areas of biological pest control does not succeed in this case. Birds pick up the larvae, but they choke it out again. It is likely that they will not get the herbal toxins that are taken up by the caterpillars with the boxwood leaves. The same applies to hedgehogs, frogs or all other brothers in arms of the hobby gardener in the fight against plant pests.

Probate insecticides

If the boxwood thaler continues to spread despite all its environmentally friendly efforts, the only option left is to resort to chemical-based insecticides. The ingredients thiacloprid and acetamipride effectively curb the adult butterflies and the green caterpillars. The following products are currently approved for use in the allotment garden in Germany:
  • Bayer pest-free calypso
  • Celaflor pest-free Careo
  • Etisso pest-free frunol
  • Compo Universal insect-free
It is an advantage to buy a concentrate instead of a ready mix. Applied with a pressure sprayer, the insecticide actually reaches deep inside the boxwood. Add a drop of detergent to lower the surface tension of the water. In this way, the agent adheres better to the smooth boxwood leaflets. It may be necessary to repeat the application. These agents are classified as harmful and require strict safety precautions when used. Since they are to be applied as a spray with high pressure, in addition to a protective clothing and a respiratory protection is indispensable.

ConclusionHer box trees have been kept under close observation by experienced hobby gardeners since 2007. Since that time, the introduced boxwood conifer is causing trouble in Germany and has since destroyed huge stocks. It is not the small butterflies themselves, but the green caterpillars that pose the deadly danger to the beautiful bushes. Fortunately, various methods have emerged in the meantime to effectively control the pests. In the early infestation stage, simple mechanical techniques help to stop the plague. In the second stage, effective biological agents are ready. Only when no environmentally friendly approach leads to success, plagued hobby gardeners resort to chemical insecticide. Successfully fighting green caterpillars in the boxwood is therefore no longer a hopeless task.

Video Board: How to Stop Caterpillars.

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