what could be causing these holes in the grass ?

Can anyone suggest what bug or creature might be causing these perfectly circular holes in my grass bed please? They are about 6-8 inches deep, half and inch or so in diameter, and there are quite a lot of them scattered over the small lawn area, which is fairly soft sandy soil, located 20 minutes from Melbourne city. No sign of any creatures, even when I've tried to check at night with a spotlight, and I doubt if they are cicadas, as the holes have been apearing for several months now. I also doubt that they are made by funnelweb spiders - I certainly hope not, and there's no web activity around the holes. The holes would appear to be empty. It's as if someone has gone around poking a round stick in the ground at irregular intervals.

another hole photo

Hello jo. I used to see these when I lived in Melbourne and we get a lot here too. You will find they are probably made by the hatching of large moths. They sometimes leave the shell near the hole. Also there are cicadas that do the same thing and you will sometimes see their shell on the ground or on a tree where they climbed up.

Jean

Hi Jean. Maybe that is it, ie. moths hatching, although I haven't seen them or any shells left behind, and there don't seem to be any cicadas or cicada shells nearby either. Certainly no cicadas are singing in the sunshine, but I think it's a bit early in the season for them.

We used to get these too when we grew in Upwey, and discovered that the culprits were yabbies!! they used to burrow and make quite large caves underground which collected and stored water for them. When I was establishing my garden halfway down the block (quite a long way, steep slope of an acre) I almost lost my spade, as the hole underground was very wide and deep and I was lucky that the ground didn't cave in with my weight. I was digging and suddenly the spade kept going and it was VERY SPOOKY!!!. took a lot of rocks and stuff to fill the hole.......

Margaret

Actually that should read lived in Upwey, not grew there!! I think my brain was somewhere else for the moment LOL

Hi Margaret, I've read about that before as a possibility, but it's a bit hard to believe that there could be yabbies here in the middle of Melbourne suburbia - there's sure not a lot of water on the surface, that's for sure. If only! I came here for Sydney 3 years ago, and the tropical downpours there are the main thing I miss.

Hi Jo, these are land yabbies, smaller than you will find in the creeks and rivers, we also have them here in Cockatoo, but not as much as in Upwey. They are apparently quite common....
We live on what was an underground watercourse, that has since dried up from the drought, (I think this is why I lost so many of my big treeferns, as they were used to the constant water supply).So I guess we may see more the yabbies too as they start needing to collect more water for themselves.....

Oh for a tropical downpour!! we did have a bit of heavy rain for about two hours on - sunday or monday - can't remember which one, added a 100 or so litres to all of the tanks each, so that helped.
Going out now to plant my Jacobean lilies, before its too late.....

Margaret