Mystery of the Autumn Cluster Moth Solved

Last month, I expressed strong suspicions that the published host plant of the Autumn Cluster Moth, Dichomeris capnites, was incorrect and that I instead suspected that this moth was responsible for the annual decimation of the local shrub Mallotus claoxyloides instead. As mentioned last post, I collected a few of the larvae swarming our denuded M. claoxyloides and attempted to rear them in a container to confirm the identity of the moths they would become. It wasn’t too long before they had formed little reddish chrysalises within the silken webbing that bound eaten leaves.

Chrysalis of Dichomeris capnites, the Autumn Cluster Moth

Soon enough, my suspicions were confirmed when what appeared to be Autumn Cluster Moths emerged a week or so later.

I was too afraid that it would escape if I lifted the plastic wrap, so this blurry photo is all I could manage

I have sent specimens of the emerged moths to the Queensland Museum for confirmation, although with the world currently gripped by the Covid-19 crisis, I am not expecting a fast reply. The moths that were emerging and congregating beneath M. claoxyloides last month have now all moved into the shady forest nearby and have gathered in their iconic clusters on broad, low-hanging leaves.

Autumn Cluster Moths, Dichomeris capnites, doing what they are most famous for

If past years are anything to go by, they will remain like this for the coming months. At Pine Mountain, Mallotus claoxyloides is the primary host plant for the species. However, this year many Alchornea ilicifolia were also defoliated by the same larvae (with the moths gathering beneath denuded plants soon afterwards). I also have a few plants of an undescribed Acalypha sp. from Bulburin National Park growing by our house. In the four years these plants have been in the ground, this is the first time they have been denuded by Autumn Cluster Moths. Interesting, the locally native Acalypha capillipes, which has much smaller leaves than the undescribed species, is not eaten by the moth. All of the host plants I have observed are in the family Euphorbiaceae, quite unlike the supposed host plant Acronychia.

With the Covid-19 pandemic in full swing I, like most people, have been spending a lot of time at home. While most of this time is spent working in front of the computer, at least I get a chance to go on lunchtime strolls. Last week, I noticed butterflies congregating at the back of one of my planted areas, and I went in to investigate. Both of my Micromelum minutum were in full flower and I have never seen such densities of butterflies swarming over the blossoms.

Butterfly feeding frenzy on Micromelum minutum

Even though this plant species has flowered and fruited regularly on my property over the past couple of years (I only planted them four years ago), I hadn’t noticed what a fantastic butterfly attractant they were until now, probably because my only bushes are tucked away behind other plants. Over the weekend, I recorded 26 species of butterflies feeding on the flowers of these two bushes and I’m sure that someone with better butterly-identification skills than me could have found several more. It’s a fantastic plant for small gardens as it is drought-tolerant, grows into a rounded shrub about 4 m tall, and flowers multiple times a year. It also produces red fruits, which I suspect are bird-attracting, but my bushes are still a bit too small to support the weight of figbirds and fruit-doves, so I am yet to see any birds eating them. Here is a collection of some of the butterflies I photographed at the M. minutum on the weekend.

Blue Tiger (Tirumala hamata), the most abundant species present

Glasswing (Acraea andromacha), which breed on the weed Corky Passionvine (Passiflora suberosa)

Female Yellow Albatross (Appias paulina)

Male Yellow Albatross (Appias paulina), showing how different the sexes can be within species

Caper Gull (Cepora perimale), which resemble a smaller, less colourful version of the Yellow Abatross

Orchard Swallowtail (Papilio aegeus), whose larvae were also feeding on the leaves of the flowering Micromelum minutum

Purple Crow (Euploea tulliolus), which was great to see up close after seeing it last year breeding on Trophis scandens up in the forest canopy.

Southern Pearl-white (Elodina angulipennis), yet another species of local white butterfly that breeds on Capparis spp.

Pale Triangle (Graphium eurypylus), which breeds locally on Melodorum leichardtii

Blue Triangle (Graphium choredon), which is not as numerous at Pine Mountain as it is elsewhere in southeast Queensland, where the weed Camphor Laurel (Cinnamomum camphora) is more widespread.

Indigo Flash (Rapala varuna)

Bright Cornelian (Deudorix diovis)

White-banded Line-blue (Nacaduba kurava)

Speckled Line-blue (Catopyrops florinda), one of numerous small line-blues that only differ subtly in size, pattern and colour.

Short-tailed Line-blue (Prosotas felderi)

Purple Line-blue (Prosotas dubious)

Large Purple Line-blue (Nacaduba berenice)

Lemon Migrant (Catopsilia pomona), the latest generation of which mostly lacks the spots present on adults one month ago.

Butterflies were not the only insects attracted to the flowers

A couple of years ago, I mentioned on this blog that the local plant Sida hackettiana attracts numerous small butterflies. Well, it turns out that several S. hackettiana were growing and flowering right next to the Micromelum. There was no contest regarding the preferred nectar source: the Micromelum. The Sida had a few small blues and yellows feeding on them, but even these species were more numerous on the Micromelum flowers.

Large Grass-yellow (Eurema hecabe) feeding on Sida hackettiana

It’s so rewarding when plants I have planted begin to support wildlife, and it’s not just the butterflies that have moved into my planted areas. While photographing butterflies, I noticed a Lewin’s Honeyeater feeding nestings in a nearby bush. I didn’t want to disturb them, so didn’t take a photo. This nest of Double-barred Finches, however, was in a much more open spot for a photograph.

Nest of Double-barred Finches, Taeniopygia bichenovii

Finches love to build nests in young Hoop Pines, as their prickly foliage provides good protection. I planted this ex-Christmas tree only last year, when it had out-grown a friend’s living room. The finches have built their nest almost entirely out of dead pieces of climbing asparagus (Asparagus africanus), so not only do they have me to thank for their building site, but also for the construction materials—large quantities of recently killed asparagus fills many of the nearby trees. I expect the chicks to hatch any day now, as the parents have been incubating for close to two weeks. I’ve intentionally avoided weeding or planting nearby over the past couple of weeks to avoid disturbing them.

Our Australasian Grebes have successfully hatched four chicks over the past week. The youngsters ride around on their parents’ backs (two can fit on each parent), or diligently follow behind when the parents are busy diving for food.

Australasian Grebes, Tachybaptus novaehollandiae

Plenty of frogs have also started to metamorphose and disperse from the dam. Four very small Green Tree Frogs (Litoria caerulea) have sensibly found their way into my nursery, where they get a misting of water each day.

Recently metamorphosed Green Tree Frog, Litoria caerulea

It’s funny how the autumn this year feels so much like spring, given how everything has sprung to life after the late summer rains.