Location: north Italy (alps)

Yesterday while watering the plants in my garden I noticed a caterpillar on my fennel leaves, and it seemes to eat them. The caterpillar is about 4cm long. enter image description here

What kind of caterpillar is this, and will it do any harm to the fennel or any other plant in my garden? I have leeks, blackberries, mint and lemon balm nearby. Should I do something about it?

It's the first year I ever plant fennel in my garden. I think I planted them on a too shady place, as they are growing over 1m high like a stem instead of growing a "bulb" at the base, so I'm not too worried if the leaves are eaten by the caterpillar.

1 Answer 1


That’s a caterpillar of a Papilio machaon, the European swallowtail.

As it feeds on your fennel, it can technically be be seen as a pest, but considering that it won’t eat enough to actually damage the fennel and that it’s classified a threatened species in some regions, I would encourage you to just leave it alone. Its favorite food sources are apiaceae, so from a gardener‘s perspective fennel, carrots, parsnips and dill - which also means that seeing it in a garden is comparatively rare, as the selection of apiaceae is way larger in the wild. None of the nearby crops you mentioned would tempt it.

  • 2
    Thanks for the answer. In this case I will leave it alone and try not to harm it - i like seeing some butterflies in my garden, which has become rare. Commented Jul 9, 2020 at 10:04

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