Monday, August 13, 2007

Lacewings and Ant-lions

Lovely to look at, but vicious to know

Lacewings and Ant-lions are predators, particularly in their larval stage. The better known ant-lion larvae live in dry sandy soils waiting for small invertebrates like ants to come by and fall into a depression and then into their massive grasping jaws. They are thus held whilst the ant-lion pierces their body with a tube, to then suck them dry. The world of insects can be a very grizzly place.

Other lacewing larvae tend to be more free moving, some patrolling the undersides of leaves in search of aphids and scale, whilst others live in rotting wood, disguising themselves with a covering of leaf/wood litter. Yet others live a semi-aquatic life on the edges of streams, feeding on aquatic invertebrates.

Both lacewing and ant-lions have wide Australian distribution, however the former are more common in the wetter eastern States, whilst the later are more common in the drier interior and western regions. As for species numbers, there are a lot of them. To give an idea, in the lacewing Order Neuroptera there are 6 superfamilies that are divided into 14 families, which in turn have a considerable number of genera and vastly more species. So yes, that little old ant-lion you once saw is only one of many species.

The well known ant-lion from the superfamily Myrmeleontoidea and the family Myrmeleontidae come in several guises, but basically they have big jaws and a body with maybe some legs for mobility. Around me is one that lives in the top couple of centimetres of sand, but instead of remaining stationary like most ant-lions, this one swims through the sand leaving snail-like trails.

To swim, it moves backwards through the sand and is propelled by a couple of paddle-like legs, one on each side of the body.

Although no threat to Olympic swimmers, it can disappear very quickly if exposed.

Ant-lion from the Myrmeleontidae family

The adults typically have four lacey wings comprised of interconnecting veins, the arrangement of which are distinctive to various groups and are an important aid to identification. The one below seems to be saying. Look at me! Look at me!

Another method to identify these insects is by their antennae, note with this species how short they are and thickened towards the tip. This places them in the family Myrmeleontidae, the Ant-lion group.

Ant-lion from the Myrmeleontidae family

The adult lacewings with their large eyes, reflect torch light and are therefore very easy to spot at night. So another reason to go spotlighting for invertebrates. You never know what you might find.

With so many Lacewing/Ant-lion species in Australia, I had to include another to illustrate some of the more obvious differences between them. Many will be familiar with the distinctively different green toned lacewings, or the bizarre mantid type with grasping limbs, but have a look at the one below. To an entomologist the differences are crystal-clear, but if you are like me, it takes a little study to see what they are.

Lacewing from the Nymphidae family

Did you spot the differences? For a start the wing reticulation is quite different, but most noticeable are the antennae, these are much longer than the Myrmeleontidae species above, plus they are not thickened at the tips. This places this lacewing into the family Nymphidae. Its larvae is probably one of those non-descript, big jawed insects that wander around on plants looking for small slow moving prey.

Before disturbing dry areas under eves or overhangs, check for inverted cone shaped depressions, as these are the places you will find your ant-lions, which in turn grow into the pretty lacewings. These are good predators by the way, and are helping to keep garden pests under control, so don't forget to leave a little habitat for them.


Gaye from the Hunter said...

Very interesting, Jack. I saw some adult lacewings last summer while spotlighting in my backyard. I was amazed to discover that they were the adult phase of antlions. They truly are beautiful things with their shimmering wings.

Since our carport has been concreted, I have not spotted evidence of antlions, however.

I am presuming that the adults eat nectar, as they appear to have lost the strong mandibles of the lavae. But perhaps they don't eat at all. Do you know anything of the adult feeding habits?

There is an amazing difference in size between the larval and adult stages. The adults that I have seen would be about 3cm, while the antlions that I have seen would be less than 1cm.

Your identifying tips will be very useful.


Esperance Blog said...

Hi Gaye,

Most adult lacewings are predators although a few do consume nectar and others plant material. Some species even have strong grasping forelegs like the Mantis Fly.

The massive grasping mandibles of the larvae are only to hold a comparatively large, strong and moving prey. The adults are probably better equipped to use its greater size and weight to restrain its victims. Remember those mandibles are only to hold the prey, once immobilised, it pierces it with a sucking tube to consume it.

Owing to the very large lacewing group it is very difficult to generalise, particularly when most people immediately think only of the ant-lion, whereas they belong to only one of many families.

When the weather warms a little, have a look at any protected dry spots around your house for ant-lion larvae, and if you spot any aphids on your plants, have a good look for large thrip-like insects, which could be other lacewing larvae.


Denis Wilson said...

Hi Jack

Denis Wilson here. I know Gaye from the Hunter has been an admirer for some time. Let me add my name to that list.

I spent some time scrolling through your posts today, and was very impressed with your photos and research. The Hakeas were especially good. I have seen some of those harsh, prickly plants (with leaves, not needles) at the Botanic Gdns in Canberra. Amazingly stiff and sharp-pointed. Your photos were great.

And the Ant-lions and Lacewings story is very good. I have tried to dig up Ant-lions, without success. I recall seeing them, in the Blue Mtns (west from Sydney) in my youth. Fascinating creatures. I have never recognised them as flying insects. Are the adults nocturnal? I know I get occasional green lacewing-like insects attracted to my front porch-light, but have not ever known enough to try to trace their life history.

I have put up a permanent link to our blog on my site - "The Nature of Robertson"

Keep up the fine work of "explaining" - you are very good at it.


Esperance Blog said...

Hi Denis, thanks for your comments and I'm glad to have you as a supporter.

As to whether Lacewings are exclusively nocturnal, I am not too sure. The ones around me certainly are, but with such a large group of insects, there are very likely to be exceptions.

In hotter, dryer climates like the interior and most parts of WA, most insects are nocturnal, probably to conserve moisture. So as the Ant-lion line prefers these dryer conditions, they are more likely to be nocturnal. Therefore exceptions to the rule may be over your way.

Thanks for your interest Denis, hope to hear more from you.


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