The burrowing wasp

We’ve had a couple of big mounds of mulch in our garden since the stump-grinding people did some work for us almost a year ago. “Leave us some mulch,” I said, and they did.

We have gradually spread it around and dug it in, but we’ve had a surprising amount of help from little friends – mostly big fat white grubs which are scarab larvae.

A big black wasp has been keen to help, too.

Flower Wasp
Wasp digging into the mulch
Black Flower Wasp
Almost gone

I’ve seen one several times in the last couple of weeks, flying up out of the heap as we disturbed it, or circling before landing and digging, but I haven’t managed a clear shot of it on the surface. This old photo, however, probably shows the same species.

As I said at the time, it’s a Hairy Flower Wasp, Scoliidae (I haven’t been able to identify it to species level but the genus is Scolia). They are “flower wasps” because the adults feed on nectar, as this one is doing. (It’s in the same genus but is not the same species – note the absence of yellow spots on the abdomen.) Their larvae, however, parasitise scarab grubs, so my wasp was digging down to lay eggs.

Our most common adult scarab is this beautiful metallic green creature. It’s in the scarab family, as are so many of our largest and most colourful beetles. I know it’s in the subfamily Cetoniinae – Flower Beetles – and it seems likely to be Ischiopsopha wallacei but I can’t be quite sure. In any event, its larvae have been very helpful in breaking down our mulch and are the likeliest targets of our wasp.

green scarab beetle
The beetle whose larvae are the target

Weevil or beetle?

Let me begin by admitting that my title question is misleading: weevils are different from most beetles in a very recognisable way but they are in fact still beetles, a family within the order Coleoptera which includes longicorns, elephant beetles and all the others.

Wikipedia informs us that Curculionidae, “the “true” weevils (or “snout beetles”) … are one of the largest animal families, with 6,800 genera and 83,000 species described worldwide.” It’s not surprising, then, that, “with so many species, a spirited debate exists about the relationships between subfamilies and genera,” (Wikipedia’s polite way of saying that the experts are still arguing).

CSIRO’s invaluable site says that weevils are, “Highly variable in form, but usually moderately to strongly convex, robust, heavily sclerotised and often clothed with scales or bristles. Head always more or less produced [i.e. extended] in front of eyes to form a rostrum, which is usually much longer than broad; antennae always geniculate [elbowed] with long scape and more or less compact club.” Many of those features can be seen in my photos of an individual I found in my garden recently:

Weevil on a frangipani branch

Continue reading “Weevil or beetle?”

Eat, Lay, Love – insects’ search for fulfilment

Life is simpler for insects than for us. Like us, they have to eat and reproduce. Unlike us, they don’t seem to want to achieve anything more than that, unless you count avoiding predators as an ambition.

These photos were taken in my garden at different times and don’t have much else in common except that their subjects are doing something more than merely resting.

Longicorn beetles (Cerambycidae) are usually identified by their exceptionally long, curved antennae. Their larvae are wood-borers and adults usually eat bark, although this one (probably a Double-coned Longicorn, Zygocera plumifera) seems to have no aversion to lichen.

longicorn beetle
Longicorn beetle eating lichen on a frangipani branch

When I started taking an interest in insects I quickly found that flies (Diptera) were far more numerous and more varied than I had guessed; better-looking and less harmful to us, too, if not positively beneficial. Many of them mimic colourful wasps, while many adults are nectar-feeders and some larvae are predators of plant pests.

The Soldier fly, Hermetia illucens, looks and behaves like a rather sleepy black wasp. Adults don’t feed at all, so they can neither bite us nor transmit diseases. The larvae are scavengers and decomposers, which makes the compost bin a particularly suitable place for the female to lay her eggs.

black fly
Soldier fly laying eggs under the lip of a compost bin lid

These lovers are also wasp-mimicking flies, Plecia amplipennis. They don’t really have a common name in Australia but are known overseas as ‘Love Bugs‘ for their habit of staying mated, like these two, for extremely long periods and even flying mated. When not engaged in this way, adults feed on nectar and pollen to keep up their strength.

black flies
Plecia mating on a bottlebrush twig

Insects enjoying the nectar

long skinny wasp
Gasteruptid wasp

Bug hunters love flowers, not just for their own sake but for the bugs they attract. This set of photos shows most of the insects I saw in just ten or fifteen minutes on one profusely flowering shrub in Anderson Park, beginning with the wasps.

blue-black wasp on white flowers
Blue flower wasp, Scoliidae

This wasp is possibly a Blue Flower Wasp, Scolia soror, and certainly a close relation if not that particular species. There was another similar one feeding on the same shrub, distinguishable by a bright yellow patch on the back of its head; it may have been Scolia verticalis (see them both here, on Graeme Cocks’ site).

Scoliidae is just one family of wasps, the Flower wasps. Gasteruptidae (top pic) is another (BugGuide calls them “Carrot Wasps” and you can see why, but I don’t think they have a genuinely common name), and there are many more including Polistinae, the Paper wasps. This index page on Graeme’s site shows them with their nearest relations, the bees and ants.

small green bee on white flowers
Green native bee

This small native bee (Colletidae) is similar to one which appeared on my earlier all-on-one-plant post. The beetle below is not just similar – it is definitely the same species:

brown beetle on white flowers
Brown Flower Beetle, Glycyphana stolata
small fawn butterfly on flowers
Lycaenid butterfly

The odd angle of this shot was forced on me by my uncooperative subject but does allow me to point out a neat bit of mimicry: the eye-spots and tails on the lower part of the wings are a surprisingly good imitation of the butterfly’s head and antennae (there’s an even more striking example here, on a related butterfly). I’m sure this is not a coincidence, since tricking predators into attacking non-vital parts is great for survival.

blue dragonfly perching on twig
Palemouth Shorttail dragonfly, Brachydiplax denticauda

All the other insects here were attracted to the flowers. This dragonfly just wanted to perch for a while and found a suitable bare twig. He happens to be the first carnivore (insectivore?) on the page and he may well be looking out for prey amongst the smaller bugs attracted to the flowers. As I said in the beginning, bug hunters love flowers.

After the rain

pink and white bottlebrush flowers on tree
Bottlebrush flowers on the tree after the rain

We had our first cyclone of the season last week but it was only a little one (Dylan, category 2 at its biggest) and Townsville  was on the northern edge of its path so its main effect on us in Mundingburra was about 60mm of very welcome rain over two days. (Some suburbs did suffer more, I know, particularly from the storm surge on the Thursday morning. I don’t mean to be dismissive of their losses but I’m writing about my own little part of the city.)

The plants responded enthusiastically to the rain, none more so than the pink and white bottlebrush (Callistemon; I think it’s  a hybrid cultivar) in front of the house.  The insects, in turn, responded enthusiastically to the flowering plants and I have had fun seeing just how many different kinds I could spot on this one tree:

brown and white beetle on flower
Brown Flower Beetle, Glycyphana stolata, a scarab
black and yellow wasp on flower
A flower wasp, Campsomeris radula
Large mosquito on bottlebrush foliage
Metallic Mosquito, Toxorhynchites speciosus

The Metallic Mosquito is a very large species but does not, thankfully, attack humans. In fact it makes itself useful to us by preying on other mosquitoes. (One expert in Thailand counted some 420 species of mosquito of which a mere couple of dozen ever fed on people. Mosquitoes are victims of their bad press just as much as spiders are.)

Green bee amongst the stamens
A small native bee, Colletidae family

There were perhaps a dozen of these bees around the tree at any one time, making them the most numerous of the insects enjoying the flowers (which included, incidentally, some tiny black beetles which were too small and dull to photograph successfully).

Taking advantage of all of them, or trying to, were some predatory spiders – Lynxes – lying in wait amongst the flowers. I saw two different species. Both these spiders are very small, about the size of a house fly.

orange-brown spider on leaf
Lynx spider (Oxyopes genus) on bottlebrush leaf. It has a grey abdomen
brown spider with spiky legs
Lynx amongst the stamens