A tiger in the bushes

Why are some butterflies called by common names such as ‘tigers’ and ‘crows’? If anyone can enlighten me, I’d appreciate it.

I saw this blue tiger (Tirumala hamata) in Ballina last week.

Blue tiger butterfly, Tirumala hamata

Near Kempsey; photo by Christa Schwoebel

These butterflies live all year round in north Queensland and migrate in spring and summer generally down to just south of the Queensland border, meaning we are pretty much at the southern-most end of their range (see the distribution map in Michael Braby’s book). But they occasionally venture further south when conditions are good for their main larvae host plants, one of which is corky milk vine (Secamone elliptica).

According to Land for Wildlife (South-East Queensland):

Corky milk vine contains several chemicals that are poisonous to many animals, but not to the blue tiger larvae. When the larvae eat corky milk vine, the poisonous chemicals get passed on to the pupae and adult butterflies. These toxins then work to protect adult blue tigers from being eaten by birds, as birds have learnt that they get sick from ingesting blue tigers.

The butterflies migrate back to the north in April and May (our autumn) and are known to over-winter in large clusters. Individuals may live up to six months.

According to Kath Vail:

The adult male butterflies are strongly attracted to the pyrrolizidine alkaloids that are also found in the Parsonsia vine, known as common silkpod or monkey rope. The male will scratch the leaves to release the sap which they imbibe, and then they convert this complex organic compound into sex pheromones.

Courtship for the blue tiger butterflies includes extensive use of hair pencils that are located at the tip of the male’s abdomen. It is quite rare in nature to see the hair pencil display; however, it involves the hair pencils being charged with perfume from scent pouches on the upside of the wing. The male then erects these hair pencils and dusts the female with the pheromones.

… It is important to plant both the corky milk vine and the Parsonsia vine together if you want to provide the most benefit to the blue tiger butterfly.

Obviously the butterflies do not feed exclusively on these vines – the Ballina example shows that. Even though these butterflies are quite common, it’s still uplifting to see them.

Finally – a Richmond birdwing!

I’ve been waiting to see the beautiful Richmond birdwing butterfly (Ornithoptera richmondia) since I moved to the Northern Rivers (18 years ago). Admittedly I have not tried very hard – didn’t go to likely places of encounter. But now I have seen one – outside the lounge room window! It’s a great, colourful thing with a most graceful, swooping flight on big wings. I thought I’d never see one, as it is a threatened species. This is a male, in the flowering frangipani tree.

Richmond birdwing butterfly (male)

The maximum wingspan is said to be about 10.5 cm, and this one seemed about that. The female is not quite so colourful, but has a bigger wingspan (up to 11.5 cm). The green  of the top of the wings of the male (photo below) first caught my attention as it sailed by.

Top view of male Richmond birdwing butterfly; photo by Department of the Environment, Water, Heritage and the Arts, Wikimedia Commons

The species is threatened in New South Wales, vulnerable in Queensland, according to Braby’s Complete Field Guide to Butterflies of Australia (CSIRO, 2016) (contrary to Wikipedia).

The Richmond Birdwing Conservation Network has a mission to increase the numbers via increasing the host plant (the Richmond birdwing vines: Pararistolochia praevenosa in the lowlands and P. laheyana in the higher areas) and also the habitat that the vines and butterflies – at all stages of the life cycle – need). The FAQ of the network gives a lot of information about the butterfly, its lifestyle and range. A short version is :

• The life cycle is a little different in higher and lower altitudes. At my place (lower altitude, below 600 metres), there are two breeding seasons when the adults emerge: between September and November and then from January to March (long daylight hours, high temperatures and high humidity).
• The adult butterfly lives for 4 to 6 weeks, while the pupa (as long as 7 cm) lasts for about 28 days in the warmer weather, longer in colder weather.
• The female lays 60-100 eggs on different leaves of the Richmond birdwing vine. From up to a few kilometres away, she detects certain chemical signals in the vines that indicate they are at a stage where the caterpillars can eat them.
• The vine is disappearing due to land clearing – once it disappears, so will the butterfly. I assume that the vine is somewhere in the vicinity of the house so I’ll have to keep an eye out for it, and for some pupas and more adults. But ‘[r]esearch has shown that the male will travel up to 4 kilometres from where it pupates while the female will travel up to 30 kilometres from where it pupates’, so it may not be that close after all.
• The adult’s yellow and red colours tell predators (pied currawong, noisy pitta, wasps) that the butterfly is toxic and should not be eaten.

When I first saw the butterfly fluttering by, I took a quick look on the ‘net and thought, ‘Holy moly, it’s a Cairns birdwing – but what is it doing here?’ Further investigation showed that it was our very own Richmond species. The Cairns birdwing (Ornithoptera euphorion) is the largest endemic butterfly in Australia, up to 18 cm in wingspan.

As chance would have it, I have a couple of pinned specimens of the Cairns species, inherited from a friend (thanks, Cate and Bill!). You can see why I made that mistake.

(Top) Female Cairns birdwing; (bottom) male Cairns birdwing, Ornithoptera euphorion

 

Exciting!

Yes, there are tigers in Australia

… and I don’t just mean the late lamented extinct Tasmanian tigers.

Butterflies of the subfamily Danainae are commonly called ‘crows’ or ‘tigers’, but I really don’t know why. Our neighbours have peacocks, but I haven’t noticed these butterflies stalking them. 🙂 Maybe the drop bears (Thylarctos plummetus) do that. I’ve been hearing them snorting every night – oh, wait, that is our local male koala (which, like the panda, is decidedly not a bear).

I found this blue tiger (Tirumala hamata) dead on the ground. It’s about the only time to get a good look at these normally fast-flitting flyers.

Blue tiger, Tirumala hamata

Underside

Adult butterflies live one to two months in summer (more if they’ve overwintered). This group eats the milky sap of some plants containing poisonous compounds such as pyrrolizidine alkaloids. These are used in the synthesis of male courtship pherones. They make the butterfly taste bitter, so providing a defence against birds.

Hmm, if birds did eat them, would that be a case of birds attacking and eating tigers? I know Australia has some odd animal relationships, but really … !

Update: They love the flowers of Buckinhamia celsissima, a native of the wet tropics of Far North Queensland, but used as a garden tree in suitable parts of Australia.

Tirumala hamata on Buckinghamia celsissima flowers; photo by Sherrie Ford

Thanks to Sherrie for the photo!

Close encounters of the lepidopteran kind

Down Copmanhurst way, about two and a half hours’ drive south of me, it’s a very different environment to the subtropics where I live. The soil on Mazza’s property is virtually sand although it’s a long way from the coast. However, it used to be under the sea millions of years ago, so that explains it.

Dry sclerophyll forest is the order of the day, with eucalypts galore. No wonder the giant wood moth, Enoxyla cinera, loves it there …

Giant wood moth Enoxyla cinereus; all photos by Mazza Verdante

This furry monster lays eggs under the bark of gum trees (see the interesting and detailed Queensland Museum Fact Sheet). The grubs are large and very edible, the larvae of another species of Enoxyla (E. leucomochla) being the archetypal ‘witchetty grub’ of Indigenous bush tucker fame. They are apparently deliciously nutty, raw or roasted.

The grubs live for about two years, then hatch into adults, which mate, lay eggs and die. The adults have no feeding apparatus, so don’t eat at all. Their sole purpose is to carry on the species.

Witchetty grub, larva of a species of Euploea that lives in the roots of wattles; photo by Sputnikcccp, Wikimedia Commons

Next we have the very common ‘common crow butterfly’, Euploea core. Members of the taxonomic family it belongs to are called ‘crows’ and ‘tigers’. The chrysalis below is full of about-to-be butterfly.

Chrysalis of common crow butterfly

Emergence …

The wings aren’t fully pumped up yet

The empty chrysalis …

Lastly, here’s a hawk moth (Theretra latreillii), one of 65 Australian species. They feed on nectar using a proboscis. According to the Australian Museum, hawk moths are the most significant pollinator of papayas.

Hawk moth, Theretra latreilli; photo by Mazza Verdante

(Many thanks to Mazza for all the photos.)

Tailed emperor butterfly

Last week I found a butterfly, wet and still and horizontal and apparently dead, on the back steps. I took it inside, thinking to add it to my meagre collection when it had dried out. A couple of days later, I noticed it was moving feebly, so I took it outside in the sun.

Tailed emperor

After a while, it opened up, sat there for a couple of minutes …

Tailed emperor warming up in the sun

… and flew away at great speed! It’s a tailed emperor (Polyura sempronius). This butterfly is common along the east and north coasts of Australia. You can see photos of the larvae and eggs here.