Hemaris fuciformis “Broad bordered bee hawkmoth”

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Robin Allen is one of the most experienced moth breeders from the United Kingdom; he often manages to rear things that completely take me by suprise, and kindly shares his knowledge with everyone.

All pictures and information on this page provided by Robin. 

This is the story of my search for Pine Hawk larvae. Except it isn’t. But it is. I was determined to find a Pine Hawk Moth larva in the UK. I have never seen the larva or the adult. I live quite far north near the top of their range, and they are not very common here, but databases of moth trap records showed that they have been present at a pine plantation 30 minute drive south.

Hang on, wasn’t this supposed to be a story about the Broad Bordered Bee Hawk Moth, Hemaris fuciformis? Why am I talking about Pine Hawk Moths instead? Well, I wanted to explain what I was really looking for, because Hemaris fuciformis was not even on my radar. It was a complete chance find.

The place I was visiting was an old pine plantation, with areas of mixed deciduous woodlands planted in a grid. Different grid sections have been cut over the decades, leaving some areas taller, some areas shorter, and some areas bare. Large pathways spider their way through the woods, with lots of sunlight reaching path edges. Lots of things like Rosebay Willowherb, Red and White Campion, and all sorts of wild-flowers can be seen along these woodland rides.

As I say, my target for the day was Pine Hawk Moths. I could just buy some, but I feel like that would be ‘cheating’. I don’t own a moth trap, and even if I did, I would then need a generator or a smaller trap running from a battery, and even then I would probably spend years only catching males (female moths generally don’t come to light traps as often as males). So my other options: Find a larva in a tree, or perhaps find a larva walking on a pathway ready to pupate. I see posts on facebook every few days in Pine Hawk season in August and September, of people further south finding them wandering on woodland pathways. So I set off with my bike or with my hiking boots, and wander slowly around the woods. With one eye, I’m watching the path beneath my feet or my tyres, and with the other eye I am scanning low pine branches or looking at the tops of small pine saplings.

One area I was concentrating on searching was an area that had been cleared perhaps a decade ago, that had newly replanted pines growing a few metres tall. As there was a lot of space for sunlight to reach the ground, there were some interesting wild-flowers among the grasses. I think some sort of Bedstraw was drawing my attention… and that was the reason I didn’t see the rabbit hole. Which is why I found myself on hands and knees, looking sideways at some honeysuckle. And that is when I became quite fascinated by the half-eaten leaf… and by what I spotted a moment later, on the stem…

This is the actual picture, taken in that moment of surprise. A new species I had never seen before, although certainly NOT the one I was searching for. I found three that day, on that honeysuckle and on another small patch nearby.

Returning the next day, I knew what to look for to make the search easier. Hemaris fuciformis has a very easily recognisable feeding pattern. When the larva hatches from its egg, it will choose a leaf and will stay there, under the midrib, eating small holes upward through the leaf. After each meal, it chooses a new area of leaf, making another small hole. Before long, the leaf is riddled with small holes along the two sides of the middle vein.

As it grows, the larva starts to take larger sections of leaf, but rarely moves more than a few inches away from its original leaf. Starting with an initial leaf, you can search up and down the nearby stems to find an older larva still feeding nearby.

Adult Hemaris fuciformis tend to spend much of their time feeding at the wild-flowers that grew along woodland rides and in clearings. For this reason, their egg laying also tends to focus on small young tender pieces of honeysuckle growing at ground level around the edges of pathways. A larva might easily survive on just a single short strand of honeysuckle just a few inches long, eating only a handful of leaves before reaching pupation.

By searching Honeysuckles for the young larva feeding pattern, and concentrating on the types of habitat most often frequented by the adults, I found 12 larvae.

Sadly, one was parasitised; When I found it, the small cocoon of just one single wasp was next to the larva. Unfortunately, the damage these parasites do to a larva is irriversible. Even though the larva looks well and healthy, internally it is a ticking time bomb. It will stand next to the wasp’s cocoon, helping to protect it from predators, until the wasp emerges.

The full grown larva is very beautiful, with a purple stripe along its underside matching perfectly with the purple stem of Lonicera. The markings around the spiracles are particularly colourful.

The other 11 larvae ranged from inch-long fifth instars, all the way down to a tiny first instar hatchling only a few millimetres in size. When at its tiniest, this hatchling was so light it could almost levitate on the hairs of the lonicera leaf.

10 of these made it through to pupation. The pupae had a very wasp-like appearance, with a pointed and striped abdomen.

I kept these pupae in a net cage in my garage all through the winter. Actually that isn’t the whole truth… One of these was lost in among the moss in which they pupated, and it remained in a sealed plastic tub in that bunch of moss, completely forgotten about, getting blown around my garden all through the winter!

After overwintering to the next spring, most of the pupae emerged into adults. I think only two pupae failed to emerge. One of those was due to a strange abnormality, whereby the two antennae had become badly misplaced when pupating — Somehow, the two antennae had twisted completely back to front. An unusual occurrence, but unfortunately fatal as such a pupa would never be able to open successfully.

The emerging adults looked like they had just emerged from the bath tub and needed a little time with a hair drier, but soon they looked a lot more pretty.

When the adults emerged, I was quite undecided where or how I would keep them. I knew I wanted to breed them, but what would work best? I had small cages, medium cages, large 1m cages, and even my garden greenhouse. Looking back, releasing them into my greenhouse was a stupid idea. For one, they immediately disappeared into the worst places. For two, they would ignore all the space and nectar flowers, and spend all their time bashing their wings to pieces against the glass of the top windows. For three, spiders are evil, absolutely EVIL! In response to the “Bee that lived for only 5 minutes”, my greenhouse’s population of spiders has seen a drastic decline in recent weeks, and so has my desire to ever release any small day-flying moths into the greenhouse ever again.

These day-flying moths do best in a net cage. If you have a large 1-metre cage, that will offer the most freedom for natural flight; but they will still spend much of their time on the cage roof. So turn the cage sideways and give them less height, but more roof space. I placed the cage in such a way that some trees gave occasional dappled shade, much as they would find in their natural environment.

I put a massive potted Red Valerian into the cage with the moths, and occasionally they did feed from it. They also took nectar occasionally from Buddleia flowers in water vases in the cage. But most often, I hand fed the moths. Despite being very flighty and unwilling to be coaxed into unfurling their proboscis, it was possible with a small pin and large quantity of patience, to get them to feed from a bottle cap.

I realised later on that the best way, is to combine both bottle-cap and natural flowers. Simply dip a small floret of Buddleia flowers into the mixture and stand it in the nectar; Now bring a Bee to it upon your finger. As soon as the Bee is brought close to natural flowers, there is a good chance that it will extend its proboscis automatically as an instinct, attempt to feed from the real flowers, accidentally miss the flowers and end up feeding heavily from the substitute nectar in the bottlecap. Most days I fed the Bees early in the day, before the warmth of the sun could warm them into very active flight.

I had several females in the cage, and I think I had at least two males in with them too. I never saw any pairings, and the females didn’t start to lay any eggs. I think keeping the males in with the females may have been a mistake. Or perhaps it just wasn’t hot and sunny enough. I never saw the females exposing their pheromone glands and actively calling for a mate.

After a week, I had a spare day on 29th June when the weather was expected to be very hot and sunny. I took the opportunity to take the cage full of females out to the original location where I found them. I spent several hours trying in different locations, sitting and waiting and hoping that a male would arrive. I took my laptop with me, and in each place I tried to call a male, I would sit and sort through all of several months of photographs in my dropbox, sorting them by species, deleting the worst and filing the best. I got through at least 8 months of photographs, and STILL no male Bee Hawks were in the air. As I walked, I could see the females were actually calling with their pheromone glands, but still no males were arriving. I had already walked a couple of miles through the woods, and was getting some crazy looks from other walkers – Do bear in mind, that as well as my hiking boots, I was carrying:

1. A large foldable but not very collapsible, and rather too heavy, bright blue chair, hung around my shoulders like a strange square pointy back-pack.
2. A silver freezer-bag full of food and drink (just in case it turned into a whole day out).
3. My laptop.
4. A 1-metre cube cage full of stingy looking scary waspy things.

I was a strange sight to behold, but you will just have to imagine what I looked like carrying all this!

It was a long, difficult hike (mostly due to all the insane things I was carrying) which took me some miles further through the woods to a clearing where I had found a high concentration of leaves showing the Bee feeding pattern the year before. If anywhere would work, then surely here would work. And sure enough, as soon as I sat down and turned my laptop on, two male Bees came flitting back and forth and circling in wide swoops around the cage. I didn’t want to open the cage door too far, as some of the females were a bit too active and could easily escape and ruin the plan. I think I counted 8 different male Bees attracted to my cage of females over the space of ten minutes. Although I opened the cage a little, the male Bees were still not finding the entrance. So instead I had to net the male Bees to introduce them into the cage. It was at this point that I remembered that I had planned to bring some sort of catching net with me. It is quite difficult to catch a male Bee Hawk with your bare hands while it is in flight.

Somehow I got three of them into the cage. The disturbance of getting the males into the cage, as well as the difference of wind movement inside a cage compared to outside, and presence of multiple females, left the males a bit confused. It took a few minutes for them to regain their senses and find the females. But find them, they did!

As I walked (chair on back, laptop in one hand, 1m cube cage full of (even more!) stingy waspy things in the other) the long walk back to my car, I was lucky to see three pairings. Clearly the females had not been pairing in the cage in my garden. I don’t know whether it was the sun and hot weather that did it, or whether it needed wild males rather than ones that had already been in the presence of the females, but the journey was a success.

In the following week the three paired females laid approximately 100 eggs, in amongst honeysuckle leaves and stems pinned at the top of the cage. Most eggs were on the foodplant, with only a small number deposited onto cage netting. The eggs were tiny, around 0.6mm in size, and were laid very infrequently – only a few appeared each day. The eggs were also very delicate, and a number of them were damaged while removing them from the cage netting.

Incubation time was just a few days, with small hatchlings only 3mm long soon appearing. The new hatchlings took very quickly and easily to honeysuckle leaves, and with so many feeding in close proximity it took just hours before they were producing the Bee Hawk feeding pattern of lacework holes in the leaves.

I also started a proportion of the larvae on Snowberry (Symphoricarpus). This Honeysuckle relative might look delicate from a distance, but when you compare it in detail you find it has much thicker stronger leaves than Honeysuckle. I was worried that the tiny 3mm larvae would struggle to bite into it, but I needn’t have worried; Soon these larvae were making good progress too.

Both Honeysuckle and Snowberry were convenient foodplants. Both would last several days before becoming unpalateable, allowing me to leave the larvae undisturbed for long periods. With the small larvae, especially around their first moults, it was useful to be able to just occasionally add a few new leaves and let the larvae find their own way onto the new stems without worrying about the old food causing problems.

I reared the larvae in plastic boxes of progressively larger size, and only at the final instar did they demand much attention. Their appetites eventually became large enough that they needed feeding every night, but that was considering that I was rearing 30+ in each box. Losses were very low, with only a few of the weakest larvae falling ill.

When searching for the larvae last year, I used the young caterpillars’ feeding pattern as a clue for where to search. If I had known at the time, there is an even easier method to find these larvae. While rearing these, I discovered that like several other green-coloured hawk moths, these larvae glow very strongly with an eerie blue fluourescence under UV light. I imagine that a trip to the woods after dark would easily have revealed dozens of them.

When the larvae reached pupation, they turned a bronze brown colour, and descended to the bottom of the box to wander or occasionally built brown net cocoons amongst leaves higher up in the cage. Each morning, I would transfer any wandering larvae into a box that I had filled with tangled up tissue paper. This is a time when I regret losing some; Even though they had a lot of tissue to form coccons amongst, I didn’t realise that most of them were congregating in a single area at a corner of the box. Cocoons built next to other cocoons, led to disturbance by their siblings, which resulted in a few deformed or damaged pupae. Perhaps 20% were lost this way, in addition to some earlier losses of weak larvae, but I was still able to produce 60+ perfect pupae.

Hemaris fuciformis can potentially produce a second generation in southern parts of Europe, but in the UK only a single generation is typical. None of these pupae have emerged in the autumn. I hope to overwinter some female pupae until next spring, at which time I think I will take another long hike to a special clearing in the woods (perhaps this time leaving non-essential items behind, taking a much smaller cage, and remembering to take a catch net), to call some new wild males.

Overall, I would rate Hemaris fuciformis as quite difficult. Why? Most the life stages are relatively easy. The eggs need no special care. The larvae can be box-reared in quite damp conditions and in high density – albeit with the risk that disease might suddenly take hold, so lower density and cleaner conditions are always preferred. The pupae can be left forgotten for months over winter and still successfully emerge. The reason for a ‘difficult’ rating is the adult stage, particularly the necessity for daily hand-feeding and the difficulty I had in obtaining captive pairings. Once the challenges of the adult stage are understood, then success is guaranteed.
Oh, and if you are wondering whether I ever found any of those elusive Pine Hawks that I was originally looking for… Well, I spent many hours in August searching acres of downed pine branches where the loggers had cleared a new section of the woods, and despite finding areas of pine needles that had clearly been eaten by something big, I came up with nothing apart from three Pine Sawflies. After riding 150 miles of Pine woodland footpaths in September, I finally found the Pine Hawk caterpillar I was looking for, wandering the footpaths ready to pupate.

Of course, it turned out to be a male. Aaaarrrgghhh. If only it had been a female, I could have used it to call a wild male. Never mind. At least I have achieved my mission to find a wild Pine Hawk!

All text, images and information on this page  user submitted by Robin Allen

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