Holly Blue perched on Red Campion leaf
Why Plant Butterfly Host Plants
Wildlife and butterfly friendly gardening is a growing topic of interest and these days most gardeners enthusiastically plant nectar rich “pollinator friendly” planting schemes.
One easily overlooked requirement is to plant for the less glamorous caterpillar stage too, but without these essential host plants, butterflies cannot reproduce.
By catering for the entire butterfly lifecycle in this way you will support your local butterfly population as well as attracting more butterflies into your garden.
This article looks at which host plants to grow to support Holly Blue butterfly caterpillars.
Holly Blue Butterfly Habits
Holly Blues are our earliest blue butterfly on the wing and, being a species of hedgerows and woodland margins, is often also seen in parks and gardens. With the right caterpillar planting scheme, Holly Blues can readily be enticed in to become a resident in your garden.
They are distinguished from other blue butterflies by their beautiful pale powder blue undersides with black spots. They also tend to fly higher up amongst shrubs and trees than their grassland relatives, which prefer to fly low skipping along amongst the ground vegetation.
Given the butterfly’s name you’d be forgiven for thinking this one's a no-brainer for planting but there's more to it than meets the eye.
Holly Blue Butterfly Host Plants
First brood Holly Blues prefer female Holly bushes, Ilex aquifolium, as their caterpillar host plant
Preferred Caterpillar Host Plants
Holly Blues are dual brooded and each generation has its own favourite caterpillar host plant. Unsurprisingly, Holly, Ilex aquifolium is preferred by the spring generation of Holly Blues. Moreover, although the first brood butterflies will lay their eggs on male Holly bushes, they have a distinct preference for female Holly plants.
BUT Ivy, Hedera helix is the preferred caterpillar host plant of the second, summer brood of Holly Blue butterflies.
Second brood Holly Blues prefer Ivy, Hedera Helix, as their caterpillar host plant
So planting a combination of female Holly and Ivy together to accommodate both brood's caterpillars is the ideal Holly Blue butterfly planting scheme.
Alternative Caterpillar Host Plants
Holly Blues will also lay on a variety of other native hedge plants and shrubs. The spring brood of Holly Blues will use Spindle, Euonymus europaeus, Dogwood, Cornus spp. and Gorse, Ulex spp.
Native hedging supports both broods of the Holly Blue butterfly
In contrast alternative planting for the summer Holly Blue butterfly brood includes Bramble, Rubus fruticosus, Alder Buckthorn, Frangula alnus , Common Buckthorn Rhamnus cathartica, also known as Purging Buckthorn and Gorse, Ulex ssp..
Gorse is in fact the only plant used by both broods of Holly Blue, which admittedly isn’t always top of a gardeners list, however a mixed native hedge, hedgerow or shrubby mini-copse or corner containing Buckthorn, Dogwood and Spindle will serve both Holly Blue generatons well and sustain the entire annual cycle of Holly Blue butterflies.
Less Common Caterpillar Host Plants
The non-native, but attractive Snowberry bush, Symphoricarpos spp has also been used by the second Holly Blue brood.
General Caterpillar Host Planting Tips
Caterpillars usually rely on our native wildflowers for evolutionary reasons, which often may not be readily available in your local general garden centre and when they are, may not be the original native cultivar or pesticide free (even with a pollinator friendly label so do take care to ask). The good news is that there are plenty of excellent specialist native plant and seed stockists online, a few of which are listed below.
Plant your caterpillar host plants in generous clumps as butterflies are often quite picky about which stems they will use. Site them in or near a sunny sheltered position (depending on the plants’ requirements) ideally with a good, seasonally appropriate, source of nectar close by. Again native plants are often preferred, when using non-natives pick single flowered varieties rather than doubles as the latter produce less nectar.
Companion Holly Blue Butterfly Nectar Plants
Most of the Holly Blue’s caterpillar host plants serve as nectar sources and honeydew is also used, but these pretty wildflowers are also a good companion planting option:
Spring Brood
Ajuga reptans, Bugle
Ranunculus spp, Buttercup
Selene dioica, Red Campion
Myosotis spp., Forget-me-not
Anthriscus sylvestris, Cow Parsley
Summer Brood
Eupatorium cannabinum, Hemp Agrimony
Carduus spp. and Cirsium spp., Thistles
Mentha aquatica, Water Mint
Ligustrum vulgare, Wild Privet
British Native Wildflower Stockists
There are plenty of online specialist suppliers these days, do ask about pesticides and double check latin names before ordering.
Emorsgate - Wildflower seed specialists based in West Norfolk
Naturescape - Nottingham based native plant and seed specialist with a good selection of plugs