December 2013

Holes in the Ground

I live next to a Bushland Reserve in Oxley.  I frequently find holes in the ground like the ones in the photograph. Can you please tell me what makes these holes that are about 10 mm in diameter?

Answer

Mystery hole at Oxley Bushland Reserve. Photo by John Lahey What do you think made this hole? Answer (1.) below. What do you think made this hole? Answer (2.) below. What do you think made this hole? Answer (3.) below. What do you think made this hole? Answer (4.) below. Our spider expert believes that the hole in your photo was made by a Wolf Spider or one of the Trapdoor Spiders as some silk lining is apparent.

Some of our most difficult questions are about holes. Holes in soil can be made by mammals, insects, spiders, crustaceans, and even birds.

Holes can be shelters for animals or exit holes left by emerging insects like cicadas or beetles. They can be exploratory excavations made by animals looking for food or permanent structures for nesting.

Biologists use the following investigations and observations to try to solve these mysteries:

  • Record the size, location and surrounding habitat. An easy way to do this is to take a photo with a ruler near the hole.
  • Shine a torch into the hole. Sometimes spiders sit near the entrance waiting to pounce on their prey.
  • Are there any sounds coming from the hole? Male Common Mole Crickets sing from their burrows.
  • Sprinkle flour or talcum powder around the entrance to see if any tracks are made coming or going.
  • Fill the hole in and see if it is re-excavated. If it is, someone lives there; if not, the culprit has moved on.
  • Look for traces of silk webbing used by spiders to reinforce the walls of their burrows and as trap lines for their prey.

Check out the four photos (on the right) from our inquiry archives. See if you can match the animal names to their holes.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ANSWERS:

  1. Golden Trapdoor Spider
  2. Wingless Burrowing Cricket
  3. Cicada nymph
  4. Funnel Ant

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