Sitting in the garden on a sunny day, you'll almost certainly not have finished your drink before a small day-flying moth catches your attention. The mint moth (Pyraustra aurata) can sit comfortably on a fingernail with outstretched wings barely spanning it, and is found in most gardens that contain mint, lemonbalm, catmint, calamint or marjoram plants.
There are usually two generations each year, in May and June and again July and August, so it’s on the wing for most of the summer. Close inspection shows dark-purple to crimson, densely furry-textured forewings, with a neat silvery-yellow rim, marked with a single golden dot on each side. The underwings are charcoal grey, with a similar but paler edge and an old-gold border halfway down.
The next generation
The mint moth (pictured below) flies close to the food plant and lays eggs on the undersides of the leaves, just visible as minute cream beads. These soon hatch into small spotted caterpillars, which loosely link two leaf surfaces together with strands of silk. The first generation feed voraciously and pupate in a small orange case within the leaves, hatching out in about six to eight weeks from an egg. The second generation of larvae pass the winter as a caterpillar, and are darker green in colour than the spring generation: they enter a semi-comatose state deep within the plant’s central rosette but will emerge and feed in mild weather.
Closely related species with bands of gold markings on the forewings, which feed on wild mints are sometimes found on chalk grassland.
The imitation game
You may also see hoverfly mimics flitting about your garden this month, which resemble bumblebees, wasps or even houseflies. Unlike the gardener’s friend, the syrphid hoverfly group, these members of the Volucella genus all live as commensals in other insect’s nests, cleaning up dead or dying adults and larvae, however, they don’t appear to be parasitic.
The hornet mimic (Volucella zonaria) is almost thumb sized and vibrates in an alarmingly hornet-like manner, even to the extent of occasionally stabbing downwards with its stingless abdomen when approached and emitting a warning buzz. It’s found from late June into autumn, and can be seen sunning itself or feeding on flowers.
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