Warning... long-winded, boring post ahead.

It's baaaaack! Cold temperatures and pounding rains have returned, just when I thought I was through with puddles in my yard. A minute ago it turned way dark outside, like the sun had set. The thermometer dropped 10 degrees and then whammo the sky opened wide up.


But that's not what I'm complaining about right now. I've been learning a bit about our good friend the Leatherjacket. I think they must be everywhere around my yard, including amongst my semps. I think they are the #1 pesky problem that I have growing semps, although it's not really that bad. Nature takes her toll and I just have to deal with that. But it does turn out that almost every time I see a problem that I can't identify above ground, it's a Leatherjack or two underground making trouble.

Here's an example. This guy below is 'Purple Haze' and looks pretty OK. But he has looked just like that for six months now. That's failing to thrive. He felt pretty solid but tugging upwards on him a bit makes it clear that he's not very solidly rooted. So I pulled him up and found exactly what I expected, a compromised root system with a Leatherjacket firmly attached. After replanting, I expect growth to continue.


Here's one of our favorites, 'Bros'. Generally a slow grower but I noticed leaves dying and he was shrinking back. Lifting him up and digging a bit reveals once again a Leatherjacket attack. This was a week ago and he's looking and feeling considerably better already. I can tell his roots are doing better.


Poor little 'Xanthoheuf' was a tiny offset when I got him and he was soon afterwards 40% chewed away. Leatherjackets sometimes come out and eat the semps above ground. When I dug under this semp I found a single Leatherjacket. 'Xanthoheuff' is still small but is rebounding quite well in fact.


I was thinning down a clump of 'Legolas' and found a Leatherjacket but the plant itself was thriving quite well. It seems one Leatherjacket doesn't bother a mature clump too much. Makes sense.

However, my colony of 'Saharasonne' was getting hammered and I thought this couldn't be the work of a single Leatherjacket. I was right... there were 4 under there. Here's the remains of that colony apparently on the mend. Set back but looking much better now.


I wonder how many are down there that aren't causing noticeable damage. I've read that in lawns you can have 25 per square foot and that won't cause a problem. 25-50 they say is a problem. I can't imagine 25 in one square foot... yikes.
I think this might be a good argument for filling your beds with a sterile, commercial mix. Or will they get into that just as readily?
Anyone else bothered with this pest?

Wow Tim. Sorry to hear that. So far I haven't had any problems with them.
For those of your that don't know what they are, maybe Tim can post us some photos?
They are the larva of the Crane Fly.

Tim maybe you could try Steinernema feltiae, a nematode that kills the leatherjack larva. You water them into the lawn/garden where they have become a problem.

This is the only photo of my own that I can locate. There are many more you can Google of course.


I'd wager most folks have LJs and don't know it. Unless you dig out and investigate suspicious situations, you won't necessarily know. And even if you have 'em, they might not be causing any real harm. Even a lost rosette here and there wouldn't be cause for panic. (unless you're me)
I can see birds yankin' them out of my lawn all the time. The birds seem to have no trouble finding them.

Good birdies!

Starlings love them, and slugs. I used to not like Starlings until I found out those two thing they like to eat.
I has been rare for us to see the Crane Fly, so I think we don't have much trouble with them. But I will certainly watch for them Tim.

These were found in both semp and xeriscape beds that I had in CA a few years back:

This was what I found within the damaged parts of my semps:
Curled up:


Unfurled and escaping:


Warning: I have shown this pic 3 or 4 times already. Sorry about that!
These were found in the soil that we were working to add cactus mix and sand. I never found these under any of my semps:


In fact, trying to identify what could have been damaging my semps was how I came to ask my first question at ATP in 2012.

Bev, your first photo appears to be a millipede. That is not what would have been causing damage to your semps. They are cleaning up the dead plant debris that is left from the damage.
Yes, again the dreaded Leatherjackets. YUCK!

What is that in Bev's last picture? It's not Leatherjackets. Looks like some sort of beetle grub.

Some sort of grub I guess. I'm clueless about bugs and their larvae forms and what they like to eat. So I have no idea. I still don't know what it was that was causing the damage to my semps for years in the CA semp bed. Seems like a lot of critters were identified to be those eating dead plant material but never an identification of what caused the damage to the main root stems of so many of my semps. It just got to the point that whenever I found a semp that pulled out of the ground real easy, I would just take the head, clean it up and place it back onto the ground hoping it would root again. A few did.

I think it is Leatherjacks that have been in water for awhile. Bleached them out.

I would bet all my raffle tickets that those are beetle grubs. Legs, distinct head with eyes and jaws, pleated body length, transparent abdomen, lateral mid line of brown dots. Those are beetle grubs, not fly maggots... there's a difference.

http://www.northeastipm.org/bm...

Yes, I finally got to see a pic of leather jacket larvae. Looks very different, smaller in size and grey in color. Never found any of those under my semps. And yes my bucket of larvae look to be more of beetle grub. And yes, that photo of the grubs is older than the larvae's time in the bucket...

Yes, I see what you are saying Tim, and agree. But even those grubs are very damaging to our plants.

From Scott's:
Grubs are the larvae of Japanese beetles, June beetles, and chafers, among others. These C-shaped creatures feast on the roots of grass and plants. To find out if you have a problem, peel back a square foot of turf or scrape back the top layer of soil in your garden beds.