Spindle Ermine Moth

To improve the reserve as habitat and increase its biodiversity, the Friends have been planting trees for years: whips and saplings of many different species to thicken the hedges and copses.

As a plan, we know it’s working. Among the species we planted was spindle (Euonymus europaeus) and last weekend, for the first time, Ian identified spindle ermine moth caterpillars (Yponomeuta cagnagella) in several sites in our hedges.

Spindle flowers and berries

The newly hatched spindle ermine moth caterpillars spin protective webs that can sometimes cover a hedge for several yards, including anything nearby: wheelbarrows, garden gates, small trees. Such webs can contain tens of thousands of caterpillars that will defoliate the hedge almost entirely.

Hatching out in large numbers is a successful survival strategy used by many insect species but large numbers can easily attract predators. Building your own shelter as you go is the next evolutionary step.

Left: Ian’s picture of spindle ermine moth caterpillars in the park; right: a hedge covered with the caterpillar’s webs.

Although they might look sinister, these webs are harmless and usually last only from May to June. They slowly disappear over the summer and typically the hedgerow recovers.

In the past, spindle ermine moths have been considered a pest species but in these dangerous times, we should be carefully reconsidering our relationship to the insects with which we share our homes and gardens. We are more than happy to see them in the reserve.

Adult spindle ermine moth [by Ilia Ustyantsev (CC BY-SA 2.0) wikimedia.org]

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