letting nature back in

Although butterflies, including citrus swallowtails, are particularly prolific in autumn, I was surprised to see a small group of butterflies gathering together while they sucked up moisture on the lawn. Even more surprising – I was able to get some photos of them as they were keen on returning to the same patch as they flitted about.

I have been thinking about doing a post on recent surprising sightings in the garden, but some of the surprises warranted a single post dedicated just to itself, such as the recently seen fabulous beetle that I wrote about here. The same applied to the unusual group of citrus swallowtail (Papilio demodocus) butterflies, as this sighting has developed into a single post about these particularly eye-catching butterflies.

Flitting and flapping as they suck on droplets of the previous night’s rain caught between the blades of grass and also absorbed by the lawn clippings, these citrus swallowtail butterflies made quite a sight as they almost jostle each other as they gather together

The butterflies were so busy in the early morning sunshine that it was quite tricky to photograph them. Perhaps the video below provides a better impression of all the activity as well as the beauty of these lovely butterflies

Amongst all the activity I captured a single butterfly in profile, showing its long proboscis extended and curved downwards as it penetrates into the grass clippings to suck the moisture retained in the grass. I wonder if the grass clippings are not fermenting slightly providing additional nutrients to the moisture

Earlier this month on an overcast day, a citrus swallowtail butterfly settled on a brick pathway enabling me to creep up behind it to take this photo. Perhaps it was trying to absorb some warmth into its muscles before flying away

This seems a good time to mention a surprising incident that took place in October last year involving a mature caterpillar of the citrus swallowtail. Appropriately enough, I came across it busily munching on a leaf of a small potted cooking-leaf lime (Citrus hystrix). As the caterpillar was eating it shook rhythmically from side to side as if to imitate a leaf moving back and forth in a breeze. I took a few photos in bright midday sun and thought I would come back later to take more photos when the light was milder.

One of the few photos I took of the citrus swallowtail caterpillar (larva) in the midday sun 

All caterpillars in the Papilio genus have a gland known as the osmetrium, which is situated behind the head. When a caterpillar is threatened it arches up and using blood pressure it shoots out the orange-coloured osmetrium that resembles the forked tongue of a snake, at the same time squirting a strong-smelling oily substance in an effort to repel predators.

After taking this photograph I went back to check on the caterpillar a few times and noted a southern tree agama hanging about on the shadecloth-covered fence of the veggie garden. I found that the caterpillar had retreated beneath a leaf where it appeared to be resting.

I had high hopes for the caterpillar – I thought that perhaps if I kept a regular eye on it I might even be able to see it pupate. The next time I went out to look at the caterpillar I nearly trod on the agama, which was near the base of the pot. The agama scuttled away and dropped something as it ran, but then it turned and came back, pausing as it climbed over a rock eyeing me intently before suddenly darting towards me to pick up something large and green near the base of the pot – it was the caterpillar! The agama grabbed the caterpillar and then turned its back on me as it softened the caterpillar in its jaws before swallowing it whole. Oh dear – the short life of caterpillar and the end of my study.

The southern tree agama glancing back at me as it climbed back up the shade cloth with its tummy bulging slightly from the bulk of the just-swallowed caterpillar

In addition to the apparent dangers of predators such as agamas, both the eggs and the pupae of citrus swallowtails can be parasitized by some species of wasps.

I did manage to take a short video of the caterpillar when I first saw it eating a leaf on the lime tree. Because it shook constantly it was difficult to get a focus. I expected to be able to return and get better photos and video – but as it turned out that was not to be on account of the caterpillar’s early demise in the jaws of the agama. But despite its iffy quality, I thought you might like to see the video anyway. The rapid movement of the caterpillar might be a bit disconcerting as it looks like I had really bad camera shake!

And so today, reading about the single egg that a citrus swallowtail butterfly lays one at a time on the leaves of its host plant, I went outside to check on the potted lime tree to see if I could see any butterfly eggs. Instead, I came across a young caterpillar in an early form (instar), black and white in colour so as to resemble a bird dropping, at least from afar – a perfect disguise.

Here is the small caterpillar I saw today. It has some way to go before it reaches the full proportions and colour of a mature caterpillar. I wonder if the small projections behind the head are related to the osmetrium gland that in a mature caterpillar is pulled inside the body and only projected when the caterpillar is under threat

Earlier this week I watched a rather wary citrus swallowtail butterfly collecting nectar from crocosmia blooms. The abundant flowering of the Crocosmia aurea is a sure sign of autumn

And then later in the day, a courting couple of citrus swallowtail butterflies caught my eye. Eventually the pair of butterflies settled while mating with one of the pair holding onto a pepperdew fruit in our herb garden. They remained like that for over an hour even while a dramatic storm (that put paid to me taking any more photos) was brewing. The last time I went to see the pair of butterflies –  as the sky was darkening ominously and heavy fat raindrops started falling – they had broken apart from each other with one remaining with wings spread. Hopefully it found shelter as 26 mm of rain proceeded to fall in the space of half an hour.

The mating pair of citrus swallowtails, when the sun was still bright in the early afternoon

The pair of swallowtail butterflies among the pepperdews as the storm clouds gathered

A close-up of one half the mating pair as it hangs onto a pepperdew fruit. It is hard to distinguish between the male and the female although the female is generally slightly larger than the male

The other half of the mating pair.  The scientific name for the order of butterflies and moths is Lepidoptera – a word that derives from the Greek lepidos (meaning scale) and pteron (meaning wing)

A closer-up view of a wing where the hairs on the abdomen (to the left) and the scales on the wing are slightly more visible

The wings of a butterfly are covered with tiny overlapping pigmented scales (which are flattened and modified hairs). These scales may produce colour by bending rays of light, much like tiny prisms or by pigments that are present on the scales. The hairs on the body and legs of the butterfly are not the same as hairs on a mammal. Many of the hairs have sensory nerve endings that make them sensitive to touch and vibration.

Perhaps the immature caterpillar that I found today on our potted lime tree will live to maturity and avoid falling prey to an agama or other predator, and so maybe this time I might be able to document a caterpillar’s progress.

 References:

Robertson, Hamish. [n.d.] Papilio demodocus (Citrus swallowtail). Biodiversity Explorer. http://www.biodiversityexplorer.info/butterflies/papilionidae/papilio_demodocus.htm; Mackean, D G & Mackean Ian. 2004-2020. Papilio demodocus – the Citrus Swallowtail Butterfly. Resources for Biology Teaching by D G Mackean. http://www.biology-resources.com/insect-papilio-01.html; Woodhall, Steve. 2013. Butterflies of South Africa. Pocket Guide. Cape Town: Struik Nature.

Posted by Carol