It's the Pits--For the Ants

I've been aware of the pits in our carport for a long time.

I knew that they were most likely antlions (Neuroptera; Myrmeleontidae; Myrmeleontinae) but I thought I should check just to be sure.

Each pit harbours this occupant. It usually is covered with soil and sits, covered at the base of the bit with the jaws agape. In the US these insects are often called Doodlebugs because they created doodle-like patterns when they move about on the surface of the of the ground after dark seeking better places to create a pit. They are very particular as to where they make a pit. They require dry, fine particles. They are at home in what might otherwise be considered as dust. That's why they are often found at the base of trees where it is dry.

We have pesky March Flies (Tabanidae, called Horse Flies in North America) around at this time of year and I decided to see if one would be acceptable to the occupant of the pit above. In no time it was attacked and disappeared beneath the dust.

Antlions are so-called because they are voracious and often feed on passing ants. If the ants attempt to climb out of the pit, the occupant flicks small pebbles at it until it knocks it down. Once in the bottom of the pit, it is usually a goner.

The antlion is a rather plump creature, well adapted for its existence in a world of dust. It is fairly mobile but does not really need to be since it spends most of its time at the bottom of its pit. It has the dubious distinction of lacking an anus. It doesn't need one. It would just pose problems-what to do with waste. Instead it stores its wastes and ejects, if that is the right word, this meconial mass (a word for your next Scrabble game) after it pupates.

Antlion jaws are formed by the mandibles and maxillae and the hollow projections inject inject venom into the prey. You can see the canal in the above photo quite nicely.

At the end of its larval career, which can last for several years, the antlion forms a pupa which will eventually produce at adult antlion.

From the web

Adult antlions are common visitors to light sheets because they are nocturnal. They are especially common in the more arid or open areas of Australia. Even though there are dozens of pits in our carport, I cannot recall ever seeing an adult at the light sheet. I have kept the cocoon to see what eventually emerges.

That's That

As a follow-up to the Slaty-grey Snake and Cane Toad incident, I thought I might have a great sequel when I discovered that Green Tree Ants, Oecophylla smaragdina, were intent on rendering the snake as protein for their nest.

 But it was not to be. Shortly after taking these photos, the snake was seen flying down the track in the beak of a Black Butcherbird, Craticus quoyi, never to be seen again Pity.

A Sad Fate for a Harmless Snake

About 80 years ago a group ill-informed, but well-intentioned, folk introduced the Cane Toad, Bufo marinus, to Oceania, including Australia. Their vested interest- protection of the sugarcane industry.

Bufo marinus, the Cane Toad or Marine Toad

The rationale behind this introduction was that the voracious appetites of the toads would be a great advantage in controlling the cane beetles (Scarabaeidae) that infest the cane, the larvae of which feed on the roots of the plants.

The knowledge of the biology of the toads and the beetles was severely wanting. Toads live on the surface of the ground and would not come into contact with the grubs of the beetles. Well, you could argue that they would feed on the adults. Yes and no. Adult cane beetles are large, 30 mm or more in length, and only an adult toad could cope with them. And, the most important aspect of all this is that when the beetles emerge from the soil they fly away from the site and only by chance would come into contact with the toads.

Two other aspects of this untimely introduction have to do with the biology of the toads. They are voracious all right. They eat just about anything they can get down their gullets. In many places they have literally eliminated the ground fauna of nocturnal insects. Not only insect, they will consume anything they can get down. Other frogs and toads and sleeping lizards (mostly small skins) are consumed.

But they other aspect of their biology has to do with their toxic nature.

Last night I had the opportunity to observe the toxic nature of these toads. A Slaty-grey Snake, Stegonotus cucculatus (Dumeril, Bibron, Dumeril) (Colubridae) was found dead in our driveway with a cane toad in the grasp of its mouth. 

The Slaty-grey Snake feeds on a variety of vertebrates but there are many incidents of cane toads causing their deaths.

This snake was stopped in its tracks by puncturing the parotid glands of the toad. These glands secrete a  powerful alkaloid called bufotoxin which acts as a neurotoxin. It seems to work quickly.

The problem with these toads in the 80 years they have been in Australia is that the majority of Australian species have no way to deal with bufotoxin. There are no native Bufo in Australia and our fauna have had no evolutionary experience in coping with it. As a result may species have been affected by the toads. Quolls seem to be especially vulnerable with virtually every individual that attempts to eat a cane toad poisoned. This is a scenario not anticipated by the group that introduced the Cane to to Oceania--I hope.

I have left the snake in place in the driveway to see if it is avoided by the cadre of Brush Turkeys that will make their way to the front door later in the morning. Heavy truck traffic on Black Mountain Road has caused the Cassowaries to avoid crossing so they will not come into contact with the toxic snake.

And that begs the question: Can cassowaries cope with cane toads? I wonder. They eat some very toxic seeds and they do eat vertebrates if they find them.

I will keep you posted.

Mantids or Mantispids

Mantispids are strange-looking insects that look like a cross between a mantis and a lacewing. They are in no way related to the Mantodea. In fact, are not even distant relatives.

One of the many grey mantispids that come to lights

Mantids are hemimetabolous insects, that is they undergo gradual metamorphosis. Mantispids are holometabolous insects, that is, they have a larval and pupal stage in their development.

The Net-winged Mantid, Neomantis australis Saussure and Zehntner

Mantispids are members of the Neuroptera, the order that includes lacewings, ant-lions, sponge-flies and the like. They are fairly common in Australia. Greyish ones a usually found at lights were they prey on smaller insects.

The mantis-like appearance of mantispids is because they both have raptorial forelegs that are used to capture insect prey.

Mantispids were generally rare and considered collector’s items in the San Francisco Bay Region where I grew up. I can still remember the first one I ever saw. It was collected by my childhood friend, who reads this blog, Charlie Cushner . It was found at Tesla Road, near Livermore, one of the favourite sites for fieldtrips when we were both members of the Student Section of the California Academy of Sciences in the mid 1950’s. So it made quite an impression. Search as I did, I did not find one on that day and was quite jealous of Charlie’s prize. It was Chimaciella brunnea Say, a species that appears similar to a Polistes wasp.

So it was like a nostalgia trip when this mantispid turned up at the light the other night. It was about the same size and colour as its Californian relative. This is identified as Euclimacia nuchalis (Gerstaecker). It is very similar in outward appearances to the California species noted above.

Euclimacia nuchalis (Gerstaecker) 

Mantispids have a complicated life history. Many are obligate parasites of spiders. They have an active triungulin larva that mounts a spider and enters her eggs sac to feed on the eggs. Some species retard the growth of their hosts by chemical interference.

Some Australian species congregate at times in great hundreds laying small eggs on stalks. But for the majority of species, we really know nothing of their life history.

To return to our story, shortly after E. nuchalis arrived, this fellow appeared on the same light sheet. Is it the opposite sex of E. nuchalis, a variant or a different species? I have no idea. But it resembles another wasp. If is the same species, it has different genetic history to one that resembles the vespid wasp. This one looks a bit like some of the pompilid wasps that seek out spiders in our part of the world. What a complicated genetic history this little insect must have.

Euclimacia nuchalis???? 

Patterns and Messages

What is the message conveyed in what we see in nature. When I look at the endless array of patterns displayed in moth wings, I wonder about the messages that are meant and interpreted by the observers. These "observers" are mostly vertebrate predators like birds and lizards.

In the 1960’s the noted Smithsonian photographer Kjell Sandved had fanciful interpretations of butterfly wings. His calendars were very popular at the time. I’m sure he would concede that his interpretations of butterfly wings were not really what nature had intended! But it does beg the question of messages and interpretation.

On the light sheet, all bets are off. Every species is present on an equal basis. camouflage, odd resting postures all mean nothing or very little to potential predators. It’s instructive to observe which creatures (mostly moths are used here) are taken and which are not. Birds find the light sheet opportune for easy pickings but the insect-eating marsupial Antechinus and lizards (mostly geckos) can often be seen harvesting the bounty.

The hungry vertebrates are not influenced by patterns on the moth wings as they view them on the light sheet—or are they. Those moths that would be camouflaged on trees or leaves are the ones that are taken first. More brightly coloured and non-camouflaged species are left alone. They are there all day. I’ve never seen a bird attempt to eat one of these moths. Whatever it is that influences their judgement, it is fairly well fixed and these creatures are left alone (avoided?). [My mothologist friend, the word merchant, is very careful about the use of words in our interpretation of natural observations].

Two moths that are not eaten by birds and lizards

This arctiid is also left alone by birds but the Green Tree Ants have no problems tearing it to shreads

 But it is not just bright colours that matter. The moth above, one of the aquatic pyaloids, is brightly coloured but is avidly eaten by the birds that visit the light sheet in the morning. Perhaps, it is some sort of pattern recognition that is at play here.

Patterns and postures are probably genetically set and learned by birds and lizards early in their lives. They seem to know what to avoid and what to try. Colours play a big role. In many groups there are mimics that are edible but possess patterns that resemble the distasteful ones. As long as their numbers are lower than those of the "models" their protection is assured. I have not observed this situation with respect to the moths above.

Rearings!

Eggs of a female Hercules Moth were recently found on Buck's light sheet. He decided to see what would happen if he attempted to raise them to maturity.

First instar Hercules moth (Coscinocera hercules Misc.) caterpillar.

 Soon the eggs hatched. And the white spiny caterpillars began to eat most of the leaves of the small Bleeding Heart tree (Homalanthus novaeguineensis). He asked me to photograph these small caterpillars and in so doing I went to my small Bleeding Heart tree to discover it was covered with another little caterpillar.

The tiny caterpillars on my tree were very photogenic.

Buck reared the small caterpillar and from its discovery on 6 October 2012 to the emergence from the cocoon on 6 November 2012 of a small moth, this is the result.

         Iscadia inexacta (Walker)                                                                   B Richardson photo

   Life cycle of  Iscadia inexacta (Walker)                                                  B Richardson photo

Note that the cocoon is formed by the caterpillar chewing small bits of the host plant and somehow joining them together.


This moth is in the family Nolidae; subfamily Sarrothripinae. The entire subfamily was formerly in the family Noctuidae.

In Ian common's book on the Australian moths he noted that the pupae of this species produce an audible sound by rubbing the projections of the abdomen against the sides of their parchment-like cocoons.