Category: Insects

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A Festive Tale: The Mistletoe Marble Moth

In this post, we’re taking a festive look at an insect that rely on Mistletoe. Humans may enjoy kissing under it, but for the Mistletoe Marble Moth, Celypha woodiana, it’s food for their caterpillars.

Munching on mistletoe – don’t try this at home!

Larva of the Mistletoe Marble Moth, Celypha woodiana. Image: Patrick Clement CC BY 2.0

It would be a bad idea for us to try eating mistletoe because it’s poisonous to humans. For the Mistletoe Marble Moth, however, this is the food plant for their larvae. These overwinter snug inside mistletoe leaves. As the weather warms up the larvae become active and feed on them throughout the spring. In the picture above, you can see the trail the larva has left as it munched through the leaf.

In early summer, when they have grown large enough, the larvae pupate. The adult moths then emerge and fly in and around woodland and orchards containing fruit trees like apple.

Mistletoe Marble Moth Celypha woodiana . Image: OUMNH

The apple trees are important because they are a host for the mistletoe plant. Mistletoe can’t grow in it’s own. It relies on other trees. The berries are very sticky and when birds eat them they clean their beaks on by rubbing them on the bark of trees, the seeds get stick in tiny crevices and begin to grow out of the tree. The mistletoe plant grows into a ball on the brach of the host tree.

Mistletoe growing on a host tree

Apples are one of the trees mistletoe prefers. Sadly apple trees are becoming more scarce in Britrain because there are fewer orchards. This means there is also less mistletoe and that means that the Mistletoe Marble moth is becoming rarer. It is a priority species in the UK Biodiversity Action Plan because scientists are worried that this species may become extinct in Britain.

Other insects on mistletoe

The Mistletoe Weevil, Ixapion variagatum Image U Schmidt CC BY-SA 2.0

This moth isn’t the only British insect that relies on mistletoe. The Mistletoe Weevil Ixapion variegatum feeds on the part of the stem behind buds and there are several bugs that feed on sap of the plant, and another that is a predator: so there can be a whole food chain on a sprig of mistletoe!

We won’t ask if you’re planning on kissing anyone under the mistletoe this year, but for those who like to bring it into the house, please remember that we also need to conserve it, and the many insects that rely on it, in the wild.

If you enjoyed reading about the Mistletoe Marble Moth, you may be interested in this article about the ways in which other insects survive the winter.

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The Intriguing Ivy Mining Bee

If you look at any ivy during the autumn there is a good chance that you will see bees on the flowers. They may look like honey bees but they are more likely to be the Ivy Mining Bee (Colletes hederae), which has a very different way of living.

Ivy Mining Bees feeding on ivy

Ivy Mining Bees can be seen feeding on ivy in late summer and early autumn, when it is in flower. Large numbers of these bees are attracted to the flowers and, because the females look very like honey bees, people sometimes think that they are all sisters from the same hive. In fact, the Ivy Mining Bee is quite different type of bee. They are a solitary species and each bee will have come from from its own individual nest.

Ivy Mining Bees are the last of the solitary bees to emerge each year, right at the end of summer when ivy is flowering. If you live in Southern England, they will probably be a familiar sight. You may not have seen them if you live further north because this bee is a relative newcomer to the UK. They were first seen on the south coast in 2001 and have since spread northward throughout England and Wales.

Ivy Mining Bee nests are often close together

These bees build their nests underground, preferring to burrow into bare ground on south-facing slopes, which is how they get the ‘mining’ part of their name. They like patches of bear earth but may also nest in garden lawns and vegetable patches. Although solitary, they like to build their nests together, so the ground can be pockmarked with dozens or even hundreds of tiny volcano-like burrow entrances.

The males emerge first and compete with each other to mate with female bees. Often several males will cluster round a single female bee. Females excavate underground burrows. In the video, you can see a female bee carrying soil out of the burrow and moving it away from the entrance with her legs.

Female Ivy Mining Bee excavating her nest.

The female bees then lay their eggs in the burrows they have made. They overwinter in these burrows, protected from the coldest temperatures. The new generation will then emerge the following year

Identifying the Ivy Mining Bee

Female bees are about the same size as honey bees and can be slightly larger. They also have similar colouration to honey bees but have dense ginger hairs on their thorax and very distinctive orange/yellow stripes on their abdomen. The males are smaller and are very similar to other closely-related Colletes species. This makes them difficult to tell apart from other species, but if you spot a bee on ivy in early autumn, it’s probably the Ivy Mining Bee.

If you enjoyed this post you might like to read about the Red-tailed Mason Bee. If you have spotted any bees out and about this autumn, why not ley us know via our Contact Us page?

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A Glorious Grasshopper

The cheerful chirping of grasshoppers on a warm sunny day has been described as the sound of Summer. One species that you are most likely to hear, and see, is the Field Grasshopper, Chorthippus brunneus.

Grasshoppers and their relatives the crickets belong to the insect Order called the Orthoptera. Grasshoppers have short antennae and crickets have antennae which are typically longer than their body. The Field Grasshopper is a common insect and is found throughout the UK. It is well-camouflaged. Its striped brownish colour often matches the grasses among which it lives. The species displays many colour variations, helping it to remain concealed, so you will often hear it before you see it.

Field Grasshopper, Chorthippus brunneus. Image credit: S Rae CC BY 2.0

Like other grasshoppers, their chirping call isn’t produced by its mouth but by rubbing its back legs against its forewings to make a sound. This is called stridulation. It is the males that make this sound in an effort to attract females. Entomologists often use these sounds to tell different species apart. The ‘song’ of the Field Grasshopper is a series of short ‘chirps’ repeated at intervals. You can listen to it on the orthoptera.org.uk website.

Chorthippus parallelus (top) has straight keels, C. brunneus (bottom) has indented keels (arrow). Image credit: OUMNH

There are a couple of other ways to identify the Field Grasshopper:

  • As you can see in the picture above, the ridges (called keels) at the sides of the saddle-shaped structure just behind the head (called the pronotum) curve inwards sharply in the Field Grasshopper (red arrow). In the similar-looking Meadow Grasshopper (Chorthippus parallelus), the keels are not indented.
  • Look at the underside of the grasshopper (if you can catch one!) . In the Field Grasshopper), it looks very hairy. In other similar species it looks smooth.

As their name suggests, Field Grasshoppers can be found in grassland in the countryside and in gardens. They feed on the grasses on which they live. The juvenile grasshoppers start hatching at the end of March. They grow through a series of stages, called instars, with the first adults appearing in June. They live throughout the summer and into late autumn. The females lay eggs in the soil which overwinter, hatching the following spring.

There is still plenty of time this year to spot field grasshoppers so why not have a look in a grassy area near you? We’d love to see any photos you take! If you likes this article, you might also enjoy watching this video about Field Crickets by Professor Karim Vahed.

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Insect Investigators 2022

By Yiwen Chen

2022’s ‘Insect Investigators’ Summer School’, organised by ‘Hope for the Future’ Project, has been a wonderful experience for me. Not only was I able to learn new facts and skills, I also took my interest in insects to the next level. I also met new people and made new friends!

Catching insects

One of my favourite activities was catching insects. We tried this at different places (like the Oxford University Park and Harcourt Arboretum)
and on different days. We were given a large sweeping net, a transparent bag, a tray, and some tubes with lids to contain the insects. The sweeping net was used in the long grass. You sweep in loops, making infinity signs whilst walking through the field. Then, a friend could help you to empty the things caught inside the net into the transparent bag. You then place it upon the tray and see what you have caught. If you want to examine it closer or if you find it unique and interesting, you can gently put the insect into one of the tubes and then use the many insect guide books (brought from the museum) to identify them.

I always felt excitement growing when looking at what I had swept up in the net. I was not only able to learn this new skill, I have also learnt about the many insects I came across: there are larvae which have three pairs of ‘real legs’ and little bags of fat for the rest; grasshoppers drop their legs sometimes to divert their predator’s attention when being hunted (the legs won’t be able to grow back if they are adults); and a wasp nest contains all sorts of hidden treasures like beetles and their larvae.

Photography

It was an absolute delight to go to the Oxford Botanic Gardens on our second day. Even more so to learn about taking photos of various insects.
Insects are small creatures, hard to spot, even harder when amongst the enchanting plants and beautiful flowers. But we were told where to look: upon the bitten leaf, beside the blooming flower, within the fallen apple… There, we find the angle, adjust the focus, and carefully, snap!

A black ant tending to a line of green aphids along the vein of a leaf they are feeding on.
Ant ‘farming’ aphids. Image: OUMNH / Yiwen Chen


As we took photos, I was able to learn more about the insects I’d found. For example, on one of the leaves of a tree, I found an ant upon a group of small insects. I later found out that the black ant was eating the sweet sap that aphids (small sap-sucking insects) produce from the tree. The ant then protects the aphids in exchange. It was very interesting. There were also many bees including honeybees and bumblebees that were all busy feeding off the nectar and pollen. This meant that they did not mind us so I was able to snap many good pictures of them. There was a Seven-Spot Ladybird on the smallest leaf of a plant, a few Flea Beetles beside some small flowers, and a Hoverfly resting on a leaf. I even saw a Red-Eyed Damselfly upon a lilypad.

red and black beetle on the edge of a lilac flower.
Image: OUMNH / Yiwen Chen
close up image of a hoverfly on a leaf.
Image: OUMNH / Yiwen Chen
close up mage of a red-eyed damselfly resting on a lilypad.
Image: OUMNH / YIwen Chen

It was stunning to see the beauty of nature around us, and to search for the hidden ones like detectives trailing clues. Photography allows me to capture the special moment and I also love it as a hobby.

Investigation

Near the end of the week, we were able to put everything we know together to create an investigation. I chose to compare the number of
grasshoppers in two different places— fresher grass and dry grass. My prediction was that there would be more grasshoppers in fresher grass than in dry grass. To make it a fair test, I used the same net, I always made 5 loops/infinity signs when sweeping, and I was always 5 steps in the grass when catching insects.

Pencil sketch of a grasshopper by Yiwen Chen.

I was very happy when my results showed that my prediction was correct, My conclusion was that there were more grasshoppers in fresher grass than in dry grass which may be because of five things. First, grasshoppers eat grass and would naturally prefer fresher grass over dry grass. Second, grasshoppers lay their eggs beneath the grass in the soil. Dry grass usually means more exposed to the sun, which means hard and crusty soil— hard to burrow through. Third, some species of grasshoppers are green so they could camouflage better in the fresher, greener grass to escape predators. Next, fresher grass means better conditions, which means a variety of different plants that could provide for them. And last, more plants and fresher grass could also attract other insects. This could either divert their predators’ attention, or work together like the aphids and ants. This was a great way to put everything we’ve learnt together. I’ve enjoyed it very much.

Hope for the Future

As I’ve said before, insects are small creatures, but they are able to make great changes to the world. Looking back and seeing all these little
creatures continuing on with their daily routines, it reminds me of their similarity with us— humans. For we are also creatures very much like them, except we have evolved and created trouble (like climate change and global warming) as well as solutions. Although this brings some sadness into me, I am also filled with hope. My hope for the future is for all humans to be brought together to face problems and to tackle them. Just like the aphids and the ants, we can help each other out. In a way, part of our future relies on insects, so we should spend our time wisely to look at them and see them for what they can do, and achieve. I believe that this ‘Hope for the Future’ Project has done an amazing job to make everything run smoothly, as well as making me enjoy every second of it! They have given me this chance to explore and learn, and I hope to take part in more of their programme!

The next event for young entomologists is ‘Entohunt’ on Wednesday 31 August 2022, 10am-12pm at the Museum. It’s free but you need to book a place in advance.

Email us at hopelearning@oum.ox.ac.uk to book a place.

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Delightful Damselflies

One of the delights of summer is seeing slender bright blue damselflies flying near water. One of the most beautiful is the Azure damselfly, Coenagrion puella.

Dragonflies and damselflies make up the order of insects called the Odonata. Damselflies are members of in the sub-order Zygoptera, meaning “paired-wings”. Dragonflies are in the sub-order Anisoptera, meaning “unequal wings”.

Damselfly
Dragonfly

You can tell the difference between damselflies and dragonflies because, in general, the body of damselflies is more slender and delicate compared to that of dragonflies. Damselfly eyes are separated on either side of the head, but dragonfly eyes are often so large they may touch. The forewings and hind wings of damselflies are the same shape, whereas the hindwings of dragonflies are broader than the forewings. Damselflies also tend to close their wings along their body when at rest but dragonflies hold their wings open. Damselflies are not as strong fliers than dragonflies and so may spend more time resting.

Newly-emerged adults are called ‘Tenerals’. They can appear very pale and may not have their mature colouration yet. You may have to look closely for any emerging markings or patterns to help identify it. Very mature adult damselflies can appear much darker.

The Azure Damselfly, Coenagrion puella, is found throughout England and Wales and in Southern Scotland near water, including garden ponds, in which the larvae develop. There is no pupa, instead, the adult develops inside the final larval stage and emerges directly from it. Adults fly between April and September, usually near water. They are about 3cm long and, as their name suggests, the males are banded with blue stripes on their black body, although the females are usually a bright green and black.

The male colouration looks similar to several other blue damselflies but can be distinguished by the pattern, especially on the second abdominal segment. You’ll have to look closely! Try taking a photo and zooming in.

Banding patterns in some similar blue damselflies

(a) C. puella has a U-shaped black mark on the upper side of this segment.

(b) In the Variable Damselfly, Coenagrion pulchellum, this ‘U’ has a ‘stem’ making it look more like a wine glass.

(c) The Common Blue Damselfly, Enallagma cyathigerum, has a marking shaped like the ‘spade’ on playing cards.

(d) In the Northern Damselfly, Coenagrion hastulatum, which is found in Northern Scotland, the ‘spade’ shape looks more like an arrow head.

(e) The mark on the Southern Damselfly,  Coenagrion mercuriale, found in Southern and South-western England and Wales, has ‘arms’ and is sometimes said to resemble a ballet dancer.

Have you seen an Azure Damselfly, or any other type? We would love to hear about it or see your pictures, of these or any other insects. You can get in touch using our Contact Us page.

If you enjoyed reading about these insects, you might like to try making your own dragonfly glider.

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Let there be Light!

When is a worm not a worm?  When it’s a glow-worm… because a glow-worm is actually a beetle!

Male glow-worms look like typical beetles with wing cases (elytra) covering their second pair of wings, but the females are very different, having no wings and resembling beetle larvae.  It is the females who emit a greenish-orange glow from their back ends by a process called bioluminescence. Light is produced by energy released from chemical reactions occurring inside the glow-worm’s body.  In nature, bioluminescence occurs in many different types of organisms from bacteria to marine vertebrates and invertebrates.  It serves different purposes such as to warn or evade predators; lure or detect prey; or, in the case of the glow-worm, as a means of communication. The female glow-worms use the light to attract males.  Male glow-worms have large eyes with a high degree of sensitivity to light, so they are well adapted to being able to spot females in the dark. Once the glow-worms have mated, the females stop glowing and lay their eggs. If you are out for a night time walk in an area of grassland in June or July, you may be lucky enough to spot these amazing insects glowing in the dark! Glow-worms can be found in England (particularly in the South), but also in lowland Scotland and Wales.

Ferocious Predators

Glow-worm larva hunting snails. Image credit: CC-BY-SA-4.0, Hans Hillewaert

It is not only the female glow-worms who can glow, however.  The larvae are also able to flash a light on and off and it is thought that this is to deter predators or to help with their night time hunting. Glow-worm larvae are ferocious hunters of slugs and snails!  They have formidable mandibles and inject toxins into their prey which paralyses and liquefies them.  The toxin can take a while to take effect so the larva may ride around on the shell of the snail, waiting for it to die! The larval stage of the glow-worm lasts for between 2 and 3 years.  Winters, when prey is scarce, are spent in a state of torpor under logs and stones, or buried in the ground. 

The Race is On!

Once the larvae have pupated, the glow-worms need to mate as quickly as possible.  They do not eat as adults and only have enough stored energy from their larval stage to survive for about 10 days before starving to death.  Hopefully with a bright lantern to attract the males, the females will mate successfully and have her eggs fertilised before dying.   

Have you seen a glow-worm recently?  We would love to hear about it.  Let us know in the comments below or via the contact us section of the blog.