The Cinnabar moth (Tyria Jacobaeae) was originally named after the bright red mineral ‘cinnabar’ once used by artists as a red pigment for painting.
The adult moth has two bright red spots and red stripes on its forewings and scarlet hind wings with charcoal edging. Moths are split into 2 broad groups – the macro moths (large) and the micro moths (small). The Cinnabar is a macro moth and has a body length of 20mm and a wingspan of between 32mm – 42mm. Although this is a predominantly nocturnal moth it can also be seen during the day.
|Cinnabar moth (Tyria Jacobaeae) © Clare Dinham|
Females can lay up to 300 eggs, usually in batches of 30 or 60 on the underside of ragwort leaves. When the caterpillars (larvae) hatch they feed on the around the area of the hatched eggs but as they get bigger and moult (instars) they mainly feed on the leaves and flowers of the plant, and can be seen out in the open during the day.
Caterpillars are feeding from July – early September and are initially pale yellow but soon develop bright yellow and black stripes to deter predators.
|Cinnabar moth caterpillar (Tyria Jacobaeae) © Roger Key|
The caterpillars feed on poisonous ragwort leaves. The poision from the leaves is stored in the caterpillars body (and even remains when they are an adult moth). Any birds or other predators that ignore the caterpillars bright warning sign will be repulsed by how foul they taste.
Numerous caterpillars on one ragwort plant can reduced it to a bare stem very quickly. They are also known to be cannibalistic.
The caterpillars overwinter as pupa in a cocoon under the ground. The adult moths emerge around mid May and are on the wing up until early August, during which time males and females will mate and eggs are laid.
Distribution and Habitat
The Cinnabar moth is a common species, well distributed throughout the UK and has a coastal distribution in the northern most counties of England and Scotland. Due to its toxicity to livestock Ragwort is being controlled in many areas across the UK. A study carried out by Butterfly Conservation and Rothamstead research in 2003 showed that although the distribution of the Cinnabar moth has remained roughly the same between the study period of 1968 – 2002 their numbers have dropped dramatically due to the persecution of their food plant Ragwort.
Cinnabar moths are found in typically well drained rabbit grazed (short sward) grassland including sand dunes and heathland and lots of other open habitats such as gardens and woodland rides.
Cinnabar moths are attracted to moth traps which is the main way of recording moths. A moth trap is essentially a light trap which is set in the evening just before dusk and left on throughout the night. Any moths found within the trap can be studied the following morning and released without harming.
|Moth trapping using a light trap © Clare Dinham|
National Moth Night
Moth night is an annual event carried out across the country aimed at raising the awareness of moths among the public. This year it is being carried out from the 21st – 23rd of June. Click on this link to find out more about National Moth Night