Ichneumon wasp
Ichneumonidae
Role in the garden
One of the largest insect families, important in biological control (Quicke, 2014). Parasitoids: the female lays her eggs in or on a caterpillar, larva or pupa of a pest; the ichneumon larva devours its host from the inside. They mostly parasitise the larvae and pupae of insects, especially of moths and butterflies.
Activity period
April to October
How to attract / manage it
Recognisable by their long slender abdomen and their ovipositor, often visible in females (sometimes longer than the body).
Practical guide
Where to find them
On umbel flowers (Apiaceae) where they forage for nectar. Females seeking hosts to parasitise: they explore leaves in search of caterpillars or eggs. Recognisable: long filiform antennae in constant motion.
Sources
- Quicke, D.L.J. (2014). The Braconid and Ichneumonid Parasitoid Wasps. Chichester : Wiley-Blackwell.
Favourite plants / resources
Related plant entries
Coriander (cilantro)
An annual umbellifer with white umbels, coriander is a valuable insectary plant for beneficial wildlife: its small, wide-open, easily accessible flowers feed bees, hoverflies and parasitoid micro-wasps (ichneumons); the larvae of the latter two keep aphids and caterpillars in check. Letting a few plants run up to flower, rather than harvesting everything for leaf, turns a row of coriander into a larder for these predators and parasitoids. Short-lived, it bolts quickly to seed in hot weather: it is best sown in succession and readily slipped between rows, as it tolerates partial shade. Traditionally grown alongside carrots and cabbages, it diversifies the scents of the bed and fills the space between slower crops.
Borage
An exceptional nectar plant, much visited by bumblebees and bees, it serves as a relay for pollinators at the edge of the vegetable garden.
Yarrow
A first-rate insectary plant: its flat umbels and long flowering season put nectar and pollen within reach of small beneficials, hoverflies whose larvae devour aphids, parasitic micro-wasps (ichneumons), bees and predatory wasps. Set along a vegetable border or sown into a flowering meadow, it acts as a reservoir of beneficial insects right beside the crops. Undemanding, it thrives in poor, dry soil, where it also doubles as a drought-tolerant ground cover. Tradition holds it to be a good companion and a compost activator, its finely cut leaves enriching the heap.
Tansy
A perennial Asteraceae with divided foliage and a powerful camphorous scent, traditionally planted as an EDGING of the orchard or vegetable garden as a reputed repellent against aphids, Colorado potato beetles, and other pests, a use that belongs mostly to popular companion planting. Its corymbs of flat button-like yellow flowers are, on the other hand, a good resource for beneficial hoverflies and ladybirds. To be contained: its running rhizomes make it invasive.