Things didn’t look good for our summer butterflies just a few short weeks ago. The cold, wet start to the season had kept their numbers low, and any sighting of any species was shared on social media. The chances of this year’s summer broods succeeding were getting less optimistic because many species were already going extinct. On many days when I went for walks, I didn’t see a single one. A friend who regularly records the butterfly transect around Bryn Euryn, the limestone hill in North Wales that is in the middle of my “patch,” set up a guided “Butterfly Walk” in the middle of this month. In preparation, he did a reconnaissance the day before, but he didn’t see many people. That night, he sent out a warning that people might want to cancel the event and try again in a week or two. No one did, probably because most of us aren’t constantly checking our emails or social media, and about 20 of us showed up as planned. We may have been a little excited because we had just been released from some of our Covid 19 restrictions (Wales has been a little more careful than England), and this was the first time we’d been able to meet up outside of Zoom since lockdown began. In the spirit of “mad dogs and English/Welsh men and women,” we set out on this very hot Sunday afternoon (the start of the heatwave) to walk to the top of the hill, which was 430 feet (131m) higher and closer to the sun, in the hopes that at least a few butterflies would be performing for us. Long grass on the cliff-edge providing perfect habitat for meadow butterflies.
Of course it was worth it, or I wouldn’t be talking about it. In just 24 hours, the number of butterfly species we saw went from almost nothing to most of the species we’d normally see here on a good day this time of year, plus day-flying moths. The number of each species wasn’t high, but most of them were new and very mobile, and with that many eyes, we didn’t miss much. But what was most interesting was seeing how these bugs affect people of all ages. Some were thrilled to see their first Dark Green Fritillaries flying quickly, while others knelt down next to a plant to watch a pair of Small Skippers mate. All of them were mesmerized by the flapping of wings and, for a short time, completely absorbed and taken to another world. Butterfly chasing should definitely be put on prescription!.
I loved being with the group and seeing the butterflies, but I missed taking pictures of the beautiful but flighty Fritillaries. Since it was still hot, I decided to go around again at my usual slow pace, and a couple of days later I set off to see if I could fill in the gaps. This time I went up the hill through the woods, where the paths and trails are shaded and it’s a pleasant degree or two cooler than on the open hillside. This is one of the best reasons to plant more trees in a warming climate, right? The first thing that caught my eye on my walk through the woods was a beautiful, fresh Comma and its shadow.
Now that the tree canopy is mostly closed, not letting much light reach the ground, there aren’t many flowering plants left, and any that aren’t able to handle the dry conditions quickly will die. Built to survive in these conditions, Wood Sage is one exception. Common Carder bees seem to really like its flowers. The annual plant nipplewort always seems to find a few nice spots along these paths as well. It has tiny yellow flowers and thin, wiry stems.
I always stopped at the fence that marked the edge of the woods to take a look at the meadow on the other side. In January of this year, the long grass was cut on a mild, sunny day. I remember thinking that was an odd time to do that, but it doesn’t seem to have made a difference because it’s now tall again, and I could see that Hogweed, Ragwort, and Knapweed were all in flower. I could also see that it was full of butterflies, mostly Meadow Browns from what I could see. This was a good sign that there would be more to see higher up where it would be easier to get to. There were clearly other bugs around, too, because what might have been a wasp or a hoverfly “bombed” my picture! Meadow with long grass and butterflies
It was hot when I stepped onto the Woodland Trail that goes around the Nature Reserve. Bugs like hoverflies would be hiding under leaves or on tree branches because it was too hot. It was very quiet because most birds are starting their “time-out” to rest after a busy breeding season and shed their old feathers to grow new ones. The total lack of a breeze was even keeping down the ever-present traffic noise from the valley below.
I left the woods and joined the Summit Trail, which was pretty much where we had started the butterfly transect on Sunday. There used to be a nice patch of long flowery grass at the bottom of this small field. But now, maybe because of more people walking on it and changes in the weather, it’s not as good for butterflies as it used to be. Today there was a Small Skipper and a few Meadow Browns flying around in the grass. There were a lot more Meadow Browns around the edges of the fields, where there is scrubby vegetation with low bushes of bramble and gorse. I counted about 30 of them, and they were all busy running around in the grass and under the brambles, not even stopping for a quick picture. It’s also hard to find wildflowers. All I could see were a few clumps of Keeled Garlic, some Lady’s Bedstraw, and the occasional Harebell. On the other side of the field, the Burnet Roses have a good crop of red hips that will turn black when they’re ready. The huge spread of Hemp Agrimony is just starting to open its flowers. One of my favorite sights right now is the Goat’s-beard flower heads that stand out like little lights in the shorter grass.
The trail goes back up through the woods from the open field, which is nice because it gives you a short break from the heat. However, the slope is steep. The clifftop with the long grass and thorny plants shown at the beginning of the post is at the very top. Over the last two days, there have been a lot more butterflies here than anywhere else. Sunday, there were about 20 of them. Today, there were so many Meadow Browns, Gatekeepers, Small Heaths, Small Skippers, one or two Brown Argus, a Grayling, and maybe even a Dingy Skipper that I couldn’t keep track of them all. Standing out amongst the crowd of brown and orange butterflies were dramatic red and black 6-spot Burnet moths. All of these species depend on tall grasses as food for their caterpillars and flowers for nectar as adults. This means that they don’t have to go far to find a good area of long grass with wildflowers. 6-spot Burnet Moth on Creeping thistle.
Along with the blue-lilac Scabious, which is a favorite of butterflies and many other insect species, more flowers had opened up because of the hot sun.
If it had been cooler, I would have stayed longer at this spot and probably found even more than I did. But it was very hot on the open hillside, and I still had to go up to the top and down the other side of the hill to find Fritillaries. When I first started exploring this hillside in 2012, it was being taken care of very differently. The long grass would have been mowed down, and ragwort would have been kept away because it was a poisonous weed. Over the years, people’s views have slowly changed, and the plant has spread a great deal. As a result, it now supports more Cinnabar moth caterpillars, some with several and others with just one or two. These plants provide important nectar and pollen for invertebrates.
On the other side of the hill, Burnet moths were the most common birds of prey. They flew low over, through, and around the grassy slope. Many of them would have just come out of their yellow alien pod-like bodies that are often seen attached to grass and other plant stems. Often there is a mass emergence, with males emerging first. The males then wait above a female’s cocoon until she comes out. As soon as she does, they pounce on her to mate before she has even had a chance to take a breath.
Common Spotted Orchids are some of the most beautiful wildflowers at this site. They grow in the grass on this side of the hill. Most of them are finished flowering now, but I found a few pretty new ones while following one of only two Dark Green Fritillaries I saw today. There was some Dropwort too, the dry limestone grassland relative of the similar-looking moisture-loving Meadowsweet.
On the other side of the trail, where the hillside is mostly left alone, Rosebay Willowherb makes a pretty pink-purple haze that stands out against the trees. Rosebay Willowherb.
Even though I tried hard, I couldn’t get a picture of a Dark Green Fritillary. It was too hot to move around, so I sat on the grass for a while and enjoyed watching the ones I did see. They are beautiful, and they fly very quickly. Luckily, I have a bunch of pictures I took earlier in the same spot. Dark Green Fritillary on Scabious.
Luckily, there were some good things that happened too. Near where I had stopped, a Brown Argus landed on Ragwort, and nearby, a fresh Gatekeeper landed on Hemp Agrimony.
As I was about to turn around and go home, my favorite summer butterfly, a small, beautiful Copper Copper, landed on a rock at the edge of the trail and then flew up to a nearby Ragwort. It was my first time seeing one this year, and it was a great way to end.
The word “aposematism” comes from the root words “apo-away” and “semantic sign.” It refers to a group of anti-predator adaptations in which a prey item’s warning signal makes it unprofitable for potential predators to eat it. Aposematic signals are beneficial for both the predator and prey, both of which avoid potential harm.
A few nights ago, I was walking on the Little Orme when I saw a black and red moth fly across my path and land on a fern leaf. I’ve taken pictures of many 6-Spot Burnet Moths in this area that are the same color but have more spots, but this one was a Cinnabar Moth, which I have always looked for but never seen until now. This is the moth that lays its eggs on ragwort. The eggs hatch into black-and-yellow-striped larvae that will soon be eating a lot of ragwort leaves.
“But common species keep the living world going and give us most of our wildlife experiences. I would argue that protecting the abundance of these species is just as important for conservation as protecting the existence of rare species.” Richard Mabey.
As a nature lover and gardener, spotting brightly colored caterpillars munching on plants is a fairly common occurrence. Yellow caterpillars with prominent black stripes are some of the most striking. But are they helpful pollinator larvae or voracious garden pests? Identifying yellow and black caterpillars down to species level provides clues to their role in your backyard habitat.
Here are some tips and photos to help you identify the most common yellow and black striped caterpillars
Characteristics of Yellow and Black Striped Caterpillars
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Prominent alternating bands of yellow and black are the defining feature. The width and sharpness of the stripes aids identification
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Look for any additional colors like white blue orange, or red spots or tufts. Hairiness, spine density, head shape and size are also important clues.
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Note the host plants the caterpillars are feeding on. Many species have preferred plant families.
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Yellow and black signals warning coloration in some species, advertising their toxicity or unpleasant taste. Others mimic this pattern for protection.
10 Common Yellow and Black Caterpillars
1. Cinnabar Moth Caterpillar
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Found on ragwort leaves.
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Thick horizontal stripes of alternating yellow and black.
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Grows up to 2 inches long.
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Toxic; ingesting ragwort makes them distasteful to predators.
2. Yellowneck Caterpillar
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Feeds on cherry, elm, and basswood leaves.
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Has long black spikes radiating from yellow bands.
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Toxic quills can sting human skin.
3. Io Moth Caterpillar
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Eats leaves of cherry, willow, elm and other trees.
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Has spiky branched spines with black tipped yellow or white tufts.
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Grows over 2 inches long.
4. Saddleback Caterpillar
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Named for its brown “saddle” markings and green body.
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Has dangerous spines that inflict painful stings.
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Feeds on a variety of trees and shrubs.
5. Fall Webworm
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Weave messy webbed tents around branches as they eat leaves.
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Yellow or pale green with sparse fine hairs.
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Feed on over 600 types of trees.
6. Gray Dagger Moth
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Yellow with black dagger outlines pointing backwards.
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Long thin tufts of hair run lengthwise along body.
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Eats elm, birch, oak, maple and other trees.
7. Orangedog Caterpillar
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Yellow with broad black stripes bordered by fine white lines.
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Covered in bristly orange spikes.
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Feeds on citrus, jasmine and other plants.
8. Yellow Woollybear Caterpillar
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The larva of the Isabella Tiger Moth.
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Very fuzzy yellow and black bands of hair.
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Eats a wide variety of plants and trees.
9. Yellowstriped Armyworm
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Larva of the beet webworm moth.
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Yellow with black stripe down center dotted with orange.
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Major agricultural pest of many crops.
10. Sycamore Tussock Moth Caterpillar
-Yellow with black bands and four white hair tufts.
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Feeds on trees including sycamore, ash, oak and walnut.
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Hairs can irritate human skin.
With some basic detective work, you can easily identify whether yellow and black caterpillars are helpful pollinators or harmful invaders in your yard. Then make informed choices about managing their populations if needed. Appreciating their diversity transforms them from garden pests into fascinating miniature wildlife.
Frequently Asked Questions About Yellow and Black Striped Caterpillars
Are yellow and black caterpillars poisonous?
Some species like the cinnabar moth and yellowneck caterpillar have toxic quills or venom and can sting if handled roughly. Teach children not to touch fuzzy caterpillars. Others are harmless despite their warning colors.
What plants do these caterpillars eat?
They feed on a wide variety of trees and shrubs. Cherry, elm, oak, birch, basswood, willow, sycamore, citrus, ash, and walnut are some favorite host plants.
Why do some caterpillars change color as they grow?
Caterpillars can change shade and pattern rapidly through molting. Their early instars are often differently colored than mature larva. This helps camouflage them while small and vulnerable.
How do you tell a yellow and black caterpillar from a yellowjacket?
Wasps like yellowjackets have more narrow bodies with a distinct waistline, along with six legs and visible wings. Caterpillars have soft, plump bodies in distinct segments and many small prolegs.
What other insects mimic yellow and black caterpillars?
Some sawfly larvae and beetle grubs mimic caterpillar warning colors like yellow and black bands. Look for subtle differences like legs and proleg count to distinguish between insect groups.
Can you touch fuzzy yellow and black caterpillars safely?
It’s best not to touch any caterpillars, especially hairy ones. While many are harmless, some have irritating hairs and spines. Teach children to look but not touch these intriguing garden creatures.
In your backyard habitat, yellow and black caterpillars play an important role in the food web. Learning to identify them by species offers insights into the diversity of life in even a small green space. So appreciate the chance to witness these colorful creatures up close, but let them munch on in peace.
Cinnabar Moth – Tyria jacobaea
Flying : May – August. UK Distribution: England, Wales, Scotland & Ireland. This plant is common and can be found in most of England, Wales, Ireland, the Isle of Man, and the Channel Islands. More confined to predominantly coastal habitats in northern England and Scotland. Habitat: It lives in open grassy places like waste ground, railway banks, gardens, and woodland rides. But it may be most common on rabbit-grazed, well-drained grasslands, mature sand dunes, and heathland.
Description: Medium-sized black moth, red markings on the forewing, hindwings mostly red. Often found near common ragwort, although sometimes on other ragworts and groundsels.
The name of this species comes from the color of the back wings and the markings on the front wings, which make it easy to spot. There are times when the pinkish markings turn yellow, the forewing is red with a black edge, or the wings are all black. Easily disturbed by day and flies in sunshine. Also flies after dark.
As a larva, the Cinnabar eats ragwort and absorbs alkaloids from it. As an adult, it keeps these alkaloids, which makes it taste bad to animals that eat it.
6- spot Burnet Moth – Zygaenea filipendula
Flying: June-August. UK distribution: Throughout Britain, mainly coastal in Scotland. Habitat: Frequents flowery grassland, woodland rides and sandhills.
Description: Medium-sized black moth with six red, occasionally yellow, spots.
Burnet moth caterpillars absorb Hydrogen Cyanide (HCN) from the glucosides in their food plants: bird’s-foot trefoil and vetches. They can also synthesise HCN themselves, storing it in body cavities and excreting it as chemical weaponry.
Also out and about in some numbers were Soldier Beetles.
