Compost critters

Brown Centipede
Centipede

Gardening is always a good way to come across the small wildlife around us and sifting compost can be among the most rewarding jobs in this way because it reveals many critters (‘bugs’, if you prefer) which rarely see the light of day.

Centipedes live in leaf litter and other moist shady habitats, and the one above was perfectly at home in the compost until we disturbed it. And why not? Cool, damp, dark, and full of small insects to eat … just about perfect. It wasn’t enormous but at just under 60mm long it was probably big enough to give someone a nasty nip and was treated with due caution during the photo shoot before being released. For more about centipedes, visit the pages of CSIRO or the Queensland Museum.

Fat white elephant beetle larvae are common in the compost, too, and we sometimes see larvae of smaller scarabs – or even the emerging adult, like this beautiful green one. We saw another of these today but it flew off before I could get a photo. All these beetles spend time underground as grubs and dig their way out after metamorphosing into their adult form. They sensibly wait until the soil softens before doing that, so they emerge in great numbers at the beginning of the Wet; we call the pretty ones Christmas beetles but I’ve got to say they are too late for that this season.

A few days ago I found a large beetle pupa (not a cicada nymph as I first thought and said) when I was emptying a plant-pot which had nothing much in it but weeds. We often see the cast-off exoskeleton of the cicada nymph, hanging on a plant like this with its back split open where the adult has emerged, and the elephant beetle larvae, but I had never seen either a living nymph or an elephant beetle pupa. One big difference which I should have noticed is that the cicada nymph has strong digging claws on its front legs but the beetle doesn’t.

Cicada nymph
Beetle pupa extracted from its underground cell
Cicada nymph on its back
Another view

This illustration of the beetle’s whole life cycle depicts a different species but the resemblance is clear.

Cairns Birdwing chrysalis

brown pupa in tree
Cairns Birdwing chrysalis

We’ve had lots of Cairns Birdwing (Troides euphorion) butterflies in our garden in the last few weeks. Every time we go outdoors we are likely to see an enormous black and yellow female or one or two of the vivid green and black, only slightly smaller, males (photos here).

And we are re-running our caterpillar-feeding problem, since our Aristolochia vines haven’t recovered from the last feeding frenzy. We have been moving the caterpillars where we can but today I saw a well-grown individual resting quietly on a rambling rose that it had nibbled for want of anything better, and I couldn’t see any more Aristolochia to move it to. I suspect its outlook there is poor but on the other hand it may be ready to pupate.

They don’t pupate on the vine but on nearby vegetation. The one above is in a bottlebrush tree which supports a vine, so it may have crawled down and or it may have made its way across from elsewhere. In any event, it is hanging just above knee height and it’s doing fine so far.

Update 5.4.14

This is kind of embarrassing but in a good way: sustained examination of the bottlebrush and the rose next to it reveals that we have about ten birdwing chrysalises, not just one or two. The lethargic caterpillar on the rose leaf has begun to pupate by making itself a silken sling like the one you can see above. (That is all it has done today, which seems like very slow progress.) We still also have large, active caterpillars – at least two on the vine in the bottlebrush.

The duration of pupation has been recorded as 26 days, according to Braby’s authoritative Butterflies of Australia, so we should be seeing them emerge around the end of this month.