Since 2007, a small, black and white butterfly and its numerous and voracious offspring have been spreading in Germany and neighboring countries: We are talking about the boxwood moth, which came here from East Asia through plant imports and is now threatening large stands of boxwood. The always hungry, green larvae, which are up to six centimeters long, currently only have a craving for boxwood and eat it bare within a very short time after an infestation. However, the eye-catching caterpillars are poisonous and should only be collected while wearing gloves.
Are boxwood borer larvae poisonous?
Boxwood borer larvae are poisonous because they absorb and store toxic ingredients such as alkaloids by eating poisonous boxwood trees. Therefore, they should only be collected while wearing gloves to avoid skin irritation.
Caterpillars only become poisonous when they eat them
However, the boxwood moth larvae are not poisonous by themselves, but because they absorb its toxic ingredients through their food - the poisonous boxwood - and store them in their small bodies. More than 70 of the various toxins, especially alkaloids, were detected in the caterpillars. The poison doesn't seem to bother them at all, quite the opposite: the caterpillars prefer to feed on the older leaves of the boxwood, which have a higher concentration of toxic substances than young leaves.
Natural predators of the boxwood borer
The reason seems obvious: their secondary toxicity makes the caterpillars unattractive as food for domestic pest killers. In the first few years it was observed that birds occasionally ate the larvae, but then spat them out again. For a long time, the boxwood borer had no natural predators and was able to spread more undisturbed. However, this seems to be gradually changing, as sparrows and great tits in particular have been increasingly sighted, not only eating the caterpillars themselves but also feeding them to their nestlings. So there is still hope that the local beneficial fauna will discover the voracious caterpillar as a source of food for themselves.
Tip
Instead of collecting the caterpillars by hand - which can be very laborious due to the often heavy infestation of several hundred to thousands of animals - you can also vacuum them with a vacuum cleaner (€72.00 on Amazon) or with a high-pressure cleaner blow out of the bush.
