A Voracious Assassin Bug
(Editor's note: This article was originally published on March 16, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to respond to your questions.)
March, in Australia, is the beginning of Autumn, and there is not a lot in flower in the garden. One plant is flowering profusely, the Garlic Chives - Allium tuberosum.
|Garlic Chives - Allium tuberosum|
First is the Dispar Skipper - Dispar compacta. This little skipper was very common on the flowers in late February, with sometimes 6 or more feeding at the same time.
Less common but still pretty regular is one of the smallest of the skippers, the Yellow-banded Dart - Ocybadistes walkeri.
|Dispar Skipper - Dispar compacta||Yellow-banded Dart - Ocybadistes walkeri|
As well as the butterflies, there are lots of flies and bees.
The bees include honey bees, but also a lot of little Reed Bees - Exoneura bicolor.
I also found one tiny little (unidentified) moth feeding at the flowers.
|Fly||Reed Bee - Exoneura bicolor||Moth |
All these insects were feeding on the flowers, gathering either nectar or pollen.
On the 3rd March I spotted a villain sharing at the feast. I found a lovely red Assassin Bug, on a flower-head, but it was not feeding on the flowers, it had its long slender beak sunk into one of the flies and was feeding on the fly.
I caught it and posed it on a leaf (with fly) for some photos.
I then collected it, in the hope of later getting a full identification. I have so far managed to identify it as a Zelus species.
Five days later, I was watching the insects on the flowers again and I saw another assassin bug on the same flowers, and again it had a fly impaled on its beak. I took some more pictures this time without disturbing the bug.
I was getting interested in this bug, so I started watching it regularly. Later in the day I saw it with another fly and a bit later still, I saw it for the first time without its prey. I wanted a picture of the bug on its own, so I went and got my camera. By the time I had returned, yet another fly was being consumed. There may be many more, but I am sure that it ate at least three flies on that day. I did later get a picture of the bug without a fly.
The next day I watched for it again. During the morning the flowers are in shade, and I saw no insects on the flowers at all, but by lunch time the assassin was back and again had a fly pierced by its beak. I wanted to see the assassin at work, so when, in the afternoon, I found the bug on a flower-head on its own, I stayed and watched closely. Twice I saw flies land near the bug on the flower-head, and each time the bug made a quick movement, but the fly escaped unharmed. A third time a fly landed just out of reach and the bug raised its head and beak and one front leg. The fly moved closer to the bug and as I watched the bug plunged its beak into the fly and the fly was doomed. I believe that the bug digests the inside of the fly and sucks it up, discarding the empty shell.
|Assassin Bug with Fly||Assassin Bug with Fly||Assassin Bug with Reed Bee|
All these food items had been flies, possibly all of the same species, but on the third day the bug was present again on its own on a flower-head. I had my camera, but needed to change lens. When I was ready, the bug had just struck on its latest prey, which this time was not a fly, but one of the little red and black Reed Bees. This last picture shows the Assassin just after plunging its beak into the Reed Bee and shows what an effective weapon it is!
We were looking on it as a welcome predator while it ate flies, but were sorry to see that bees are also on his diet!
PS. After writing this, I wandered back to the garlic chives, while my wife proof-read the article.
|Flower Spider with Fly|
The Assassin was resting below the flower-heads (digesting a large meal perhaps), but I realised that he was not the only predator stalking the garlic chives. On one of the flower-heads, I spotted a little Flower Spider - Diaea evanida. The spider was down among the flowers and I lifted it on my finger. It immediately abseiled down a thread and I arranged that it land on top of the flowers. It stayed where it landed and when I moved in close to take a photograph, I found that the spider had also caught a fly on the flower-heads and had its fangs buried in the body of the fly.
A second predator was benefiting from the attraction of the flowers. Quite a complete little ecosystem on a small patch of garlic chives!