Bug of the Day

Check out the antennae on this Common Bagworm Moth (Psyche casta) I found on the side of my house last June. The name “bagworm” comes from the fact that the caterpillars of this species creates a larval case made up of blades of grass. I often see these “bags” attached to fences, the side of my house, the undersides of leaves, and other flat surfaces in my yard.


Case Moth caterpillars, family Psychidae, use silk and plant materials to build a case around themselves, and extend their head and thorax to feed. There is a rear opening for excreta.

This individual, probably Clania lewinii has fixed its case to the branch with a loop of silk. When disturbed it retreated inside the case, and tightened the loop, drawing the case opening up under the twig. Neat.

Psychidae, also known as Bagworms, are a relatively small Lepidopteran family. Upon hatching, the larvae often construct cases out of silk and plant material, which is then suspended from leaves and branches. After pupation, only the adult male will leave, with the female remaining in the case awaiting the male. Following copulation, the female will then lay her eggs in the case, and then die. 

Photo taken by Connor Butler - Ipoh, Perak, Malaysia.


Faggot Case Moth caterpillar in its case, Psychidae by Andreas Kay
Via Flickr:
from Ecuador:


A couple of days back we went to a nursery where I noticed a chrysalis on one of the macadamia saplings. I decided that seeing as the previous cocoon I found had been disappointingly occupied by a slug maybe I’d have better luck with this one and actually get to watch a moth or butterfly emerge in the near future. So I took the little branch it was hanging from and popped the lot in my handbag to take home!

In the car I was afraid it might get accidentally squashed so I carefully removed it from my bag and tentatively examined it once more to confirm it wasn’t empty like the last one. That’s when I noticed it – little insect legs clutching the twig it’d been dangling from with a bit of silk not long ago…

I love insects. I love watching insects. What I don’t love is the thought of being trapped in an enclosed space with an unidentified mystery creature hiding in a bag which only reveals parts that look scary as hell! I’m wondering at this point whether there’s any spiders who nest like this and I’m trying to remember what wasp’s legs look like and just generally freaking out until this thing pokes its head out.

After a friendly identification from Ben, turns out I picked up a large bagworm (Matura elongatus) from the Psychidae family!

They’re generally found around the eastern parts of Australia where we’re located and feed on a wide variety of native plant species including Eucalyptus and Acacia. They spend the entirety of their youth dragging themselves around in this bag until eventually pupating in it as well, at which point they become either a magnificent black and orange male moth or an average white and brown, flightless female moth who will continue to spend the rest of her life in the cosy comfort of her sleeping bag (presumably with snacks and Netflix to keep her company).

This was hanging from a tree, it looked to me like a chrysalis, but I’ve never seen one like it. Is it from an insect, or just a piece of the tree?

It is in fact a cocoon (chrysalis’  typically have butterflies in them), the cocoon of a bagworm moth (Psychidae). These guys like to collect random materials and encase themselves in them. They typically move around in them but once they start to pupate (which yours is) they cement themselves to a surface and wait to undergo metamorphosis.