National Insect Week 2020

Overbury celebrates insects big and small during National Insects Week.

This week is National Insect Week 2020, it encourages people of all ages to learn more about insects. Often when you think of farming the immediate insect that springs to mind is a bee. However, there are many other insects that play an equally important role within the ecosystem. One insect we thought of as being particularly beautiful is the Moth, although often overlooked. We asked our wildlife advisor Pamela Clarke if she could share some interesting facts about these colourful insects.

Moths are a major part of our biodiversity and play vital roles in the ecosystem, affecting many other types of wildlife.  Moths benefit plants by pollinating wild flowers whilst feeding on their nectar and so help in seed production:  they also are vital to our food crops which also depend on them whilst both adults and their caterpillars are food for a wide variety of wildlife, including other insects, spiders, frogs, toads, lizards (there are actually 3 varieties of lizard in the UK), shrews, hedgehogs, bats and birds.

Many species of moths and their caterpillars (as well as some mammals such as the badger and skunk) use aposematic signals (from the Greek apo ‘away’ and sema ‘sign’) – to warn predators to keep away.  These brightly coloured and often striped signals are beneficial for both predator and prey, since both avoid potential harm.  The most common and effective colours are red, yellow, black and white. 

The Cinnebar moth Tyria jacobaea is predominantly a night flying insect but is seen by day resting in grassland.  It has distinctive pinkish-red and black wings whilst its caterpillars have alternating orange and black bands.  They use members of the genus Senecio as their food plants – commonly Ragwort S. jacobaea which contains alkaloid poisons.  As the caterpillars feed on the leaves they store the poison and this is passed from pupa and subsequently to the adult.  By advertising  colourful visual warning cues the caterpillar is protected as is any potential predator – save for the cuckoo which will eat cinnabar moth larvae. Similarly Tiger moths advertise their unpalatability by their warning colours and in some species by exposing a flash of red underneath: they can also produce ultrasonic sounds which warn bats to avoid them.

As the caterpillars feed on the leaves they store the poison and this is passed from pupa and subsequently to the adult.  By advertising  colourful visual warning cues the caterpillar is protected as is any potential predator – save for the cuckoo which will eat cinnabar moth larvae. Similarly Tiger moths advertise their unpalatability by their warning colours and in some species by exposing a flash of red underneath: they can also produce ultrasonic sounds which warn bats to avoid them.

Burnet moths are characterized by conspicuous protective aposematic markings with long, narrow wings are glossy black with red spots.

The Six-spot Burnet Zygaena filipendulae is a day-flying moth commonly found in grasslands and on woodland rides and it feeds on the nectar of Knapweed, thistles and other grassland flowers.  Its yellow and black caterpillars feed on Bird's-foot Trefoil Lotus corniculatus.

 

Similarly with the Five-spot Burnet, at all stages of life this species is highly noxious containing hydrogen cyanide making it very distasteful to birds. 

 

These species have developed strategies to help them survive.  At landscape scale all moths are highly valuable to farmland diversity and their conservation is urgently needed since their rate of decline is alarming.  From experiments conducted involving moth-trapping on intensively farmed land hedgerow trees and wide field margins locally enhance macro-moth diversity.  Research suggests that these features could help to reverse negative trends for farmland biodiversity if implemented over sufficiently large areas providing a network of key habitat resources.