I have had holes made in my garden from mice and chipmunks, but your holes seem too small. Is there a university in your area with a horticulture program? Maybe they could help you. Have you asked any people in your community? Good luck.
Could it be earthworm holes? Sometimes after rain or heavy watering they will come to the surface. They leave little round holes when they do.
We have digger bees coming up everywhere now, but their hole has a mound of dirt around it.
I agree with Calalily as well, but I have one other possiblily. Parasitic wasps. Last year I had a number of june bug size larvae in the garden and I would see dozens of these wasps digging holes in the garden, then tucking these larvae three times their size into the holes. Appartenly they deposit their eggs in the larve before inserting them into the holes. I watched several of them digging their nest holes and they were amaizingly quick. They did not leave a pile of dirt around the holes like a worm does after a rain.
Well HoneybeeNC, if you liked that one I've got one YOU will really enjoy. We call them 'Orange Backs". Bumble bees which also dig holes in the ground, but not the garden. Early each spring we get a growing collection of these bumble bees which are about 2/3's the size of the black/yellow variety roaming the garden. They are actually partial to tomato buds if I get an early enough start. This year we even saw some more the size of a regular honey bee, but still have the brilliant, fuzzy, bright orange thorax. I have spotted them coming from holes in uncultavated areas and was hoping to figure out some way to increase their numbers. Read about an method to cultivate bumble bees using a three pound coffee can and some insulation. Might work for the orange backs. I'm making up several for next spring. Unfortunately they disappear after about a months time, but they are really busy buggers for that short period of time.
Another night owl heard from. This is what I used to find the article twiggy buds...see if that works for you. Make a Bumble Bee House.mht
The article was written by Dave Pehling in "Bug of the Month Supplement" and is called "Coffee Can Cottages for Bumble Bees". A very discriptive article with some nice pictures as well. I have another project to build Mason Bee houses. A whole different approach. Last year we had literally hundred of these on my wife's pepperment plant which was moved to the back yard nearer the garden. Unfortunately I didn't see any of the mason bees this year and they are great polinators. Interestingly enough they have a very narrow range of travel. In order to get mason bees started you need to take some of the houses out to the forest to collect them. There are many varieties of mason bees so you may have to try several locations to collect the ones most beneficial to your garder. Either way these critters are said to out perform the regular honey bee which we don't generally see until later in the season after temperatures warm up a bit.
Glad you found it. Didn't know if I had enough information. I am a bit surprised at the number of nightowls here. I am about to crash for a couple of hours but It's nice to know there are people to talk to here in the wee hours. Some times I forget where I posted something and don't find responses until much later. I feel foolish for not tagging them as watched threads, but I have a number of threads I watch, and never seem to have enough time to go through all of them. Besides the fact I am a year behind. Thankfully we have long cold winters here...I guess.
Thanks for the info., Calality. Mine must be pollinators since they are the first bees to begin pollinating the tomato buds. I'm not sure the coffee can nest would work for these even If I burried the can in the ground, exposing only the lid and a small opening. Guess it's worth a try though.
saanansandy - as a former beekeeper, I know how sad it is that our friend the honeybee has to face this terrible, mysterious disease :(
Because I see so few honeybees in my own vegetable garden, I have put up a Mason Bee hive, although it is another native bee that actually lays her eggs in it. I've not been able to identify the species. Last spring there were thousands of these little bees in the garden - then we had one of those late spring freezes, and everyone of them vanished! I assume they could not take the cold, and died :(
One thing the article did not address: These little native bees will NOT sting unless they are provoked. When they come into the house, I gently steer them into a cup, and take them back into the garden.