Sunday, July 19, 2009

Summer World III: Ant Lions

Here in this part of New Hampshire you live in sand — beautiful, soft beach sand. John showed me, quite a few weeks ago, creatures that like to live in the sand — ant lions. You can see the indentations of each ant lion home in these photos. Above, John is tickling an ant lion sand pit in order to get the ant lion to reveal itself. Some of the pits have no inhabitants, so tickling the pit is the only way to find out if it is being lived in. The ant lion thinks that the grass leaf is an ant and jumps out of the bottom of the pit to eat the ant.

Above, John has captured an ant lion. This one was really tiny and difficult to focus on with the Canon XSi. When ants walk into an ant lion's sand pit, they can't often escape. As they crawl out of the pit, the sand keeps them sliding back down until the ant lion gobbles them up.

Ant Lions (or Antlions or Doodlebugs or Doodle Bugs)
(Genus Neuroptera, Family Myrmeleontidae)
Above you can see the tiny ant lion.
It has enormous pinchers in front.

Below: I showed the sand pits to Wingnut, who promptly began feeding ants to the ant lion. It was totally fascinating to see the capture process. We noticed that about half of the ants were able to escape the pit. But half couldn't escape and were eaten. A 50% kill rate is pretty good in Nature. It is very difficult to see the escaping ant in the photo below.

After these activities (when these photos were taken), I happened to read Summer World because Bernd Heinrich's books have taught me so much about where I live. Summer World has a great section on ant lions (pages 193-194). If you live in New England (especially northern New England) you must read this book. You should read it if you live anywhere else:
". . . ant lions . . . are slow-moving predators that catch fast ants. They do this by making pits in lose, dry sand. The pits serve as traps; the ant lions hide buried in sand at the bottom of the traps with only their sharp tonglike pincers exposed; and with these pincers they grab any ant that wanders in. If an ant then starts to scramble up the steep, slippery slope of dry sand, they throw up loose sand that starts a sandslide and brings it back down and into reach.


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