grubs in pile

[drh146]

Grubs that I normally would find under my lawn are showing up in my compost pile in large numbers. Are they ok for the pile, and should I sort them out before using my compost in my garden?

[JOHANDER]

Grubs are esencial in your compost. They are the best "organic eaters".

You can see a lot of grubs species.

Could you send a photo?

[drh146]

Sorry it took so long.
This is average size

[rainbowgardener]

Looks like Japanese beetle or some relative. I definitely would get rid of them before you use your compost. I find the occasional one in my compost, not large numbers of them, but when I find them, I toss them on to whatever sidewalk or driveway is handy (that they can't burrow in to) and leave them as a treat for the birds.

Not sure I would have said they are essential in a compost pile, since they aren't detritivores. The grubs normally eat the living roots of grass. Things that are essential in compost piles are the detritivores that eat and break down dead stuff, like earthworms, pillbugs, etc.

[JOHANDER]

Thanks for the photo.

Probably is a Cetonia aurata grub.

This grup is harmful for your garden, but not for your compost.

I agree with rainbowgardener, I recommend you rid of them before use your compost.

I have seen this grub in a compost with high Ph level.

[drh146]

Any recommendation on how to get rid of them? Is there something I can mix in my compost to kill them or make them want to move out

[rainbowgardener]

I have never had lots of them in my compost, but I would think if you sift your compost, which lots of people like to do anyway for finer texture, all the grubs would be left behind on the sifter to be disposed of.

[drh146]

Is there anything organic I can put in my pile to lower the Ph?

Should I put bt in it? Where can I get it?

[applestar]

Wood ash in compost being discussed here https://www.helpfulgardener.com/forum/vi ... 35&t=55816

...Bt ... Are you thinking of milky spore? I don't think there are Bt targeted for Japanese beetle type grubs.

How often do you turn your compost? When I turn mine, the wild birds and other critters like chipmunks seem to go over the pile for any tasty treats that may have turned up. People with chickens can let them have a go at the compost pile.

[DoubleDogFarm]

People with chickens can let them have a go at the compost pile.

or ducks

[rainbowgardener]

Wood ash is used to raise the pH of compost pile, not lower it. Drh was hoping to lower the pH to drive the grubs away.

I don't know, because compost piles naturally tend to neutralize themselves over time, so anything acidifying you would add to the pile (citrus peels, pine needles) would move to more neutral as it breaks down. You might try covering the pile (like with a tarp) and not turning it. Anaerobic decomposition is more acid producing.

https://whatcom.wsu.edu/ag/compost/funda ... linity.htm

but generally for composting we try to avoid anaerobic conditions, because they cause a lot of other problems, including stench.

So you could just throw in a bunch of citrus peels and hope that the pile being acid for awhile is enough to drive them away, even though it neutralizes later.

But I still think they aren't such a big problem and could be just sifted out at the end. And I should modify my statement above. I think they are in the compost pile because they help break down stuff in the pile. They are first level decomposers and like to eat healthy living roots, which is why they are in the lawn, but also will eat the dead stuff in the compost pile.

[drh146]

I was putting lots of wood ash in my pile last spring, and maybe that's why I am where I am.

Citrus stuff sounds like a pretty good idea, so I'll start doing that.

I have been sifting, but its nice to not have to.

[imafan26]

You can add sulfur to the pile to acidify it. The sulfur needs to be broken down by the microbes in the soil so it takes 3-6 months to actually see the change.

The compost we made on site, even the vermicompost tested at close to a pH of 8. Since the soil I have in that garden has a pH of 7.8, and sulfur takes so many months to work, the compost team tried added the sulfur to the compost while it was being processed and it worked. The finished compost ended up being close to neutral.

It is nearly impossible to permanently change the pH of the native soil since the forces that keep the pH in that range will always bring it back. However, it helps not to aggravate the problem by not adding any more alkaline material. I cannot grow certain things because they do not like the conditions and I use pine needles as an acidic mulch and must regularly add sulfur to get the pH down closer to 7.2. Compost does help to buffer the pH so it behaves more neutrally but I would rather not add an alkaline compost.

Most compost piles start out acidic but become more alkaline as the bacteria and fungi in the compost consume the nitrogen. It is even more alkaline if wood ashes and high calcium materials like cabbages and comfrey are used in quantity. Adding chicken manure will increase the pH in the pile by 0.5. Unless you have acidic feedstock, many finished composts will test out between 7.5-8.5 and not neutral. The only real way you can tell what your compost finishes at is to have it tested. I have tested piles a few times, but since in general similar feedstock is used, the results are fairly consistent. It does make it easy to adjust because knowing the average pH of the finished product makes it easy to figure out how much sulfur to add to the compost to have it finish in the neutral range.

https://www.ipm.iastate.edu/ipm/hortnews ... 94/ph.html
https://extension.umass.edu/vegetable/ar ... -fertility

[toxcrusadr]

The other question is, are you observing symptoms of serious Japanese beetle infestation? In other words, if they're doing damage, you do need to reduce their numbers. I see them now and then whether digging in the garden or the compost, but I don't have a major problem with the lawn roots or other plants (which the adults eat). One year we had a major attack on a small oak tree, sprayed them, haven't had a problem since. As long as the population stays within limits, it's not a big problem.

[drh146]

No, I don't see any damage from them. I do have lots of them, but I never find them in the actual garden. And in the summer they mostly eat... Well let's say I notice they're a big help when I go to pick up after our dogs before mowing ...

And the grass seems to do fine with them.

[applestar]

Oh! Then these must be dung beetle larvae, right? It would make sense then that you might find a number of them in the compost.

I was puzzling over this thread because I usually don't find Japanese beetle grubs in the compost. I've never seen dung beetles in my garden though I have heard they do occur around here in horse pastures and farm areas.

[rainbowgardener]

As noted, I do find Japanese beetle grubs in my compost, but only like one or two in the pile, not in any numbers.