The very hungry caterpillar

black caterpillar
Caterpillar of Impatiens Hawk Moth on a well-eaten twig of Pentas. Its head is at the right.

Hawk Moths (Sphingidae) are a family of large, heavy-bodied moths whose caterpillars are similarly large and heavy-bodied, and they get that way by eating voraciously.

The Australian Museum says:

The caterpillar of the Impatiens Hawk Moth, Theretra oldenlandiae, is a common visitor to suburban Sydney gardens. It is most frequently found on Balsams, Impatiens balsamina, I. oliveri and I. wallerana, often eating all the leaves. Some other larval food plants include:

  • Arum Lily – Zantedeschia aethiopica
  • Fuchsia (any of the garden varieties)
  • Grape – Vitis vinifera

The caterpillars are black with yellow spots and strips, and have a thin spine at the end of the abdomen that has a white tip. Mature larvae can reach a length of 7 cm. The larvae pupate in a loosely woven cocoon, which they construct within leaf litter.

… Although they may eat your plants as caterpillars, hawk moths are not considered pests. The adults have an important role as pollinators of many plant species and are the most significant pollinator of papaya (pawpaw) crops.

Hawk moth caterpillars regularly attack just two species of plants in our garden, the Pentas and Madonna Lily, and one or two caterpillars can, and do, strip a plant in a matter of days. The one in my photo was evicted from a white-flowering pentas to give it (the plant!) a chance of survival.

The same site notes that Australia has 65 species of hawk moth (all the adults are shown here, with links to the caterpillars) of the 850 known worldwide. I’m not sure how many of them we have around Townsville but I have photographed adults of seven species and caterpillars of about six in my garden. (Caterpillars are hard to be sure about because each species can have two or three colour forms.)

I only have caterpillar-adult pairs of four species, however, so we have at least eight species altogether: Convolvulus Hawk Moth, Agrius convolvuliEupanacra splendens; Grapevine Hawk Moth, Hyppotion celerioHippotion rosettaDaphnis protrudens; White-brow Hawk Moth, Gnathothlibus erotus; Impatiens Hawk Moth, Theretra oldenlandiae; and Macroglossum micacea. Note that most of them don’t even have ‘common’ (i.e. English-language) names but have to get by, somehow, with Latin. I don’t think it bothers them.

Caterpillar season

Our Wet season is the ideal time for caterpillars since that is when their food plants are growing best, so it makes sense that the Wet is also peak butterfly mating and egg-laying time. In the last week or so I have seen lots of Migrants, Eggflies and Crows and observed both mating and egg-laying; I have also seen a few Hawk-moths and know they have been similarly busy. Here are two caterpillar stories from the last few days.

The Common Crow

orange caterpillar with black and white stripes
The very colourful caterpillar of the Common Crow, Euploea core, on a Desert Rose

Don Herbison-Evans says this caterpillar is usually found on Oleander but is also known to feed on Frangipani. The Desert Rose, Adenium obesum, is a member of the family Apocynaceae, as are both of these, so the Desert Rose is a logical addition to the list. The adult butterfly is a rather plain black and white creature, as the name suggests:

Common Crow 7733
Common Crow, Euploea core, on snakeweed (an exotic pest species, but the butterflies love it) on Cape Pallarenda.

I saw one of them alight on the Desert Rose, curl its abdomen around and lay an egg … then went and got my camera:

Egg of Common Crow 8382
Egg of Common Crow on Desert Rose

The egg is about 1.5 x 1 mm and a close-up of it is here. What will happen to it when the flower opens, I wonder?

The Hawk-moth

green caterpillar
Young Hawk-moth caterpillar on what’s left of a pentas leaf, one of their favourite foods – in our garden, at least

Hawk-moths are quite large and heavily built and so are their caterpillars but this is a very young one, about as thick as a toothpick and two-thirds as long. The tail-spine and the eye-spots are characteristic. A gallery of older individuals, both caterpillars and adult moths, may be seen here.

 

What’s around – mid February

Green Katydid
Katydids have much longer antennae than grasshoppers. This nymph's antennae are about twice its body length.

Our Wet has been pretty half-hearted so far. We have had showers and storms but nothing like the widespread soaking rain that we expect.

If I had to summarise what’s happening now in our little world of insects, the key word would be ‘green.’ There has been enough rain to encourage all the plants to grow, and the plant-eaters – especially grasshoppers and hawkmoth caterpillars – are taking advantage of the abundant food. Not only that, most of them want to stay camouflaged and so they are as green as what they eat.

More systematically:

  • Grasshoppers: lots of young ones, plus some young Katydids (mentioned here because Orthoptera covers Grasshoppers, Crickets and Katydids).
  • Butterflies: Pale Triangles (some yellow form now as well as the blue variety); Common Eggfly and Blue-banded Eggfly, but all of them males; Migrants and Crows; passing Ulysses, always special; occasional Orchard Swallowtails and what looks like a caterpillar; a fair number of Hesperidae; still no Eurema or Junonia.
  • Moths: Lots of little grass moths; a few adult hawk moth sightings, and lots of their caterpillars munching their way through our Pentas.
  • Mantis: still a few Neomantis nymphs on the weed I found them on, but they seem to leave home as soon as they can fly.
  • Dragonflies: a few in the garden, lots more closer to permanent water.
  • Flies: lots of red-eyed blue blowflies (Calliphoridae), some Soldier Flies, Stilt Flies and little, long-legged, green flies (Dolichopodidae) but hardly any Hover-flies (Syrphidae). Mosquitoes are Diptera (flies) too, and they are making up for the shortfall in the numbers of their relatives.
  • Wasps and bees: a few active mud-daubers and paper wasps; not as many Ichneumonidae as there were a month ago; a few Resin bees and Blue-banded Amegilla bees.
  • Spiders: some Lynx and Jumping Spiders, and quite a lot of Silver Orb-weavers. A few adult St Andrew’s Cross spiders, and a lot more to come because I have seen hatchlings. Still no little spiky Austracantha; and still no big Golden Orb-weavers  although last year we had them from December through to June.
Jumping spider and grasshopper
This grasshopper was not well enough camouflaged and not quick enough, and the Jumping Spider got him.

Hawk moths

Convolvulus hawkmoth, Agrius convolvuli
Convolvulus hawkmoth, Agrius convolvuli

Like the Rhinoceros beetle (previous post), hawk moths are wet-season visitors, with occasional strays turning up as late as the end of May and as early as the end of October. We get several species – Hypotion rosetta and some adults I haven’t identified such as this camouflaged brown one. They generally feed on the wing, like this one.

They often fly in around dusk so we don’t see them as often as we see their caterpillars, which spend all day eating their way through our Pentas plants and will do the same to Madonna lilies if given the chance. (We might like them a bit more if they liked the weeds, actually.) The caterpillars are large – here is one on my hand to give you an idea – and come in green, brown or black, often with eye-spots and usually with a horn on the tail end.