Let’s not wait for the rain

brown bugs
Shield bugs mating on the trunk of a guava tree

Townsville is still waiting for the rain – all we’ve had is a 12mm teaser nearly a week ago – but the garden is coming to life anyway. I spotted this mating pair of shield bugs (aka stink bugs, Poecilometis sp., Hemiptera, Pentatomidae) a few days ago, and they are not alone. Hawk moth caterpillars are stripping our pentas plants and madonna lilies (I wonder why they like those two in particular?) and we often see courting pairs of Cairns Birdwing butterflies. Other butterfly numbers are building up, too, especially the Pale Triangle and the Clearwing Swallowtail.

Abundant invertebrates

black butterfly attacking a black and white one on a pink-flowering creeper
A Common Crow, Euploea core, attacking a Marsh Tiger, Danaus affinis, feeding on Maiden’s Blush creeper

A week ago I mentioned my surprise and disappointment at how few bugs I found in a Hobart garden in the week after Easter. One of the expert Tasmanian bug-hunters I mentioned in that post was amused by my reaction:

I had a good laugh at your disappointment … Unfortunately you did come down at the beginning of the ‘slow’ period (especially bad April to August). We do have winter insects but for the most part it’s more a specialist pursuit of the very small critters :-)

In retrospect, I think there were two reasons that the low numbers surprised me. One is that my memories of childhood in South Gippsland (the nearest thing to a Tasmanian climate I have experienced) have probably been skewed by the fact we didn’t spend much time outdoors in winter, as well as blurred by the decades in between. The other is that I hadn’t really thought about the difference between Tasmania’s seasonal variation and Townsville’s. We have comparatively little variation in day length or temperatures and our far greater variation in rainfall seems not to matter quite so much. (N.B. the temperature scales on these two charts are the same but the rainfall scales are not.)

Hobart monthly temp and rainfall Townsville monthly temp and rainfall chart

A stop on the way home from Reef HQ Aquarium on Thursday drove home the difference quite emphatically, although quite by accident. I pulled up beside a mangrove creek which runs through a narrow strip of parkland between South Townsville and Hermit Park (something I have done several times before – see this post and links from it) and in the space of half an hour or so I was able to photograph, not just observe, more species of butterflies and more species of true bugs (Hemiptera) and more species of spiders than I had seen in my entire week in that South Hobart garden. I also saw, but didn’t photograph, another species of butterfly, some small grass moths, two species of native bee and various flies.

The links on this list mostly lead you to older photos, here on Green Path or on my Flickr photostream, but a couple taken on the day deserve more attention. One, showing the kind of behaviour that makes the observer rethink butterflies’ sweetness-and-light reputation, is featured at the top of this page.

orange-black bugs on twig
Assassin bug nymphs

Assassin bugs (Reduviidae) are common enough but this was the first time I had seen new hatchlings (here is a bigger one in the same parkland). They were dispersing down the mangrove twig away from the cluster of eggs they had just emerged from.

 

 

 

I am an ant! Really!

Ant-mimicking Hemipteran nymph uid 5268I lie.

I am not actually an ant at all, but looking like one may save me from critters willing to eat harmless vegetarian bugs like me but unwilling to attack nasty-tasting, big-jawed ants.

Starting again, a bit more seriously: these photos show a couple of insects I found together in my garden recently. The first is about 6mm long, the second about 8mm. My first and only thought was that they were ants, although the transparent rim around their bodies looked strange for an ant (and just as strange for anything else) and so did the bracket-shaped shoulder-piece of the larger one.

Ant-mimicking Hemipteran nymph uid 5253I uploaded both photos to my Flickr photostream and the good people from the Field Guide to Australian Insects and Encyclopedia of Life Images soon put me on the right track: “I’m guessing that these are close to the Broad-headed Bugs (Alydidae). Both seem to be immature stages and the wings have yet to develop completely. The adult would have wings covering the abdomen,” and, “not an ant but an Hemipteran nymph … it vaguely resembles other ant-mimic bugs in the family Nabidae I know from Europe,” and, “Definitely an ant-mimicing heteropteran nymph. We (Aussies) have numerous species spread among several families that have ant mimics as nymphs,” and, “Semi-transparent seams give the impression of several constrictions, where there are none!” (Clicking on the images on this page with take you to Flickr, where you can see the whole discussion as well as full-size photos.)

In this light, the puzzling features weren’t so odd: I know a native cockroach  and a beetle which have transparent edges to their coloured carapaces, and the ‘shoulder-piece’ is simply a pair of wing-buds.

Once the right track, I succeeded with an image search. The best match I found was on Brisbane Insects’ invaluable site, Rhyparochromidae – Seed Bugs, which told me that Rhyparochromidae is a family closely related to Lygaeidae (Seed Bugs, Milkweed Bugs and Chinch Bugs). They are small dull brown or blackish bugs which eat seeds; many of them are flightless.  When (if) my bugs become adults, they should look something like this or this (not my photos), with wing patterns mimicking the ant-like body segmentation.

These bugs are far better ant-mimics than the jumping spiders I found a while ago. Some of their relations are pretty good, too – visit Brisbane Insects’ ant-mimicry page to see them.

Spotlit bug

red and black bug spotlit against dark background
Spotlit sap-sucker (Hemiptera)

When we are photographing small insects, the available light is crucial: we need a small aperture for the depth of field, which means a long exposure time (in which the bug might move) or a lot of light. We therefore use flash quite often.

The effect is frequently unnatural, since the flash illuminates the subject without reaching the background, but can be attractive. This shot is typical: the little sap-sucker was hanging around in a shady part of the Palmetum late in the afternoon – not the middle of the night as one might think – and the vegetation behind it has vanished into stygian gloom.