Swallowtail butterfly
Papilio machaon
Role in the garden
A large butterfly (63-75 mm wingspan according to the LPO), yellow and black with characteristic “tails”. The green caterpillar, striped black with red dots, feeds on Apiaceae: carrot, fennel, dill, parsley (locally rue, around the Mediterranean), easily seen in July-August.
Activity period
April to September (one to three generations a year depending on climate)
How to attract / manage it
Important: if you see green caterpillars on your carrots or your fennel, DO NOT KILL THEM, they are swallowtails. Losing a few leaves is well worth the encounter.
Practical guide
Where to find them
Adults in rapid gliding flight over flowery meadows, at the edge of woods and the vegetable garden. Caterpillars: on Apiaceae (cultivated and wild carrot, fennel, dill, parsley, parsnip), from June.
Prevention
Let a few carrots, fennel and dill bolt into flower. Accept a few caterpillars on your Apiaceae: your harvest will not suffer. If too many, gently move the caterpillar onto a wild fennel at the edge. No insecticide, even organic.
Sources
- LPO : fiche espèce Machaon (lpo.fr)
- Lepi'Net : Papilio machaon, le Machaon (lepinet.fr)
Favourite plants / resources
Related plant entries
Carrot
In the vegetable garden, the carrot is planned first and foremost around its pest, the carrot fly, hence the value of interplanting it with onions. Its taproot needs loose, deep, stone-free soil (RHS), without a heavy application of manure just before (GAB/FRAB Bretagne). And when left to flower, this umbellifer opens up umbels that feed hoverflies and other small beneficials, like the other Apiaceae so valued for drawing in pollinators and aphid predators.
Fennel
Reputed to hinder its neighbours (effect shown mostly in the laboratory): grow it apart as a precaution. But very useful to pollinators, and a host plant of the swallowtail.
Parsnip
Its taproot needs deep, loose, stone-free soil (RHS); in this site's rotation, parsnip comes before the legumes. Its umbel flower, in the second year, feeds hoverflies and small beneficial hymenoptera.
Dill
A major apiaceae for attracting pollinators and helpers (hoverflies, ichneumons, lacewings) to its yellow-green summer umbels. To be let go to seed. Self-seeds faithfully. A classic companion of the cucumber, to be avoided in direct contact with the carrot, which mature dill tends to outcompete.