Green Alkanet and Scarlet Tigers

A visit to Avon Wildlife Trust’s wild plant nursery Grow Wilder in Frenchay is always a treat and not just for the cake in the cafe. A couple of years ago I bought some plants for my little garden with the aim of increasing the pollen sources for bees.

One of the plants that I purchased was Green Alkanet (Pentaglottis sempervirens). It is a lovely plant to have in the garden even if it is considered a “weed” by some. Despite the name, the flowers are blue, the “green” refers to the leaves which do not fully die down in winter and grow quickly in early spring. It is a relative of forget-me-not, borage and comfrey and is a very good food plant for bumblebees, solitary bees, hoverflies, and orange tip butterflies.
Strictly speaking, although widespread, Green Alkanet cannot be defined as “native” - it was introduced to UK gardens in the 1700’s. As is common with many plants that are unfairly considered as unwanted weeds in our over manicured gardens, it has historically had medicinal uses; herbalist Culpepper recommended it for a number of ailments from burns to smallpox.

 Additionally the roots go quite deep and as such bring nutrients and chemicals to the surface which other plants may not. If your garden gets overrun with the plants, a good “tea” can be made to add nutrients back into the soil. Wear gloves to pick the leaves as the hairy stem can cause irritation and let the plants rot in a bucket of water to use as a plant food - or more simply (and probably less smelly!) chop up the leaves ( but not the roots, as the plant will spread from small sections of root) and add to the compost heap. 

It was particularly exciting to see some tell-tale circular holes in the leaves of this, now not so little, plant in mid-March. On investigation, I found that the culprits were two caterpillars of the Scarlet Tiger moth. Hopefully there are more.
The females like to lay eggs on comfrey and nettles, but in this instance Alkanet seems to have been the plant of choice. After seven days they will have hatched and overwintered as 15mm caterpillars in the leaf litter. They become active in March and as they get larger they may wander off to find other plants such as bramble to munch on.

When they get to 45mm long they will spin a cocoon and pupate, emerging about a month later as a gorgeous moth.

Scarlet Tiger moths (Callimorpha dominula) are one of many that fly during the day. The adults can be seen in June and July in South West England. Last year I saw, what I presume to be, the parents of these little caterpillars in my garden resting on runner bean leaves or amongst leaves on elderberry bushes. 

When their wings are closed they have dark forewings with white markings but if disturbed they will show their bright red underwings which gives an indication that they are mildly toxic to any potential predator. 

It was great to find the caterpillars and now have a great excuse not to tidy up the soil around the base of the plant so that I can look forward to seeing the lovely adult moths in summer.

Julia Shahin

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