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Cicada larva are eating my plants roots.....how do I kill them?

 
Paul Gurnsey
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I have been digging in my garden and found many grubs......which I have identified as cicada larva....I have given every single one of them swimming lessons in a bucket full of water and it seems that none of them can swim.....which is good. If digging is the only way to find and kill these nasty frackers I may as well give up. I know that locating the eggs on trees and killing them before they start will eliminate this problem. How do I kill the ones living in my soil and eating my plants roots? I had 10 tomato plants and 9 of them died because of these bstrds. The only reason the last one didnt was because i kept piling fresh soil up onto the base of the dying plant so new roots could grow and keep it going. This didnt work for my eggplant or peppers.....god rest their souls.
 
R Ranson
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What a frustrating challenge.  I feel for you as I've done the grub battle before.

Have you grown any of the larvae to adulthood yet?  It can be surprising as they don't always grow into what we expect.  I think the first step would be to gather a few, put them in a jar with a handful of dirt, some of their 'food' and put a cloth on top so they can breathe.  Once they hatch, you can get a professional identification for free from the good people at bugguide

If they are Cicada Larvae then you have a delicious source of protein.  Much better nutrition than vegetables.

There are lots of little things you can change to discourage pests.  Is the soil too acid, to alkali, too wet?  Knowing exactly which grub this is will show you ways to change the soil so they never come back.

Another solution is to save your own seeds.  Next year, grow a selection of different cultivars and then save seeds from the ones that the bugs don't like.  In a couple of years, you can have a tomato that is virtually grub proof.  I had the same problem with march fly grubs and fava beans a couple of winters back.  A couple of plants thrived while the others withered.  I saved the seeds from the thriving ones, now I have almost no problem with march fly grubs even though they are still prevalent in the soil.


 
Paul Gurnsey
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But all i have is shovel. I feel so inadequate.
 
Casie Becker
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Beneficial nematodes prey on a lot of ground dwelling larva. We spray them for fire ants, but they take care of lawn grubs and flea larva also. I don't know for sure that they'd prey on cicada grubs, but it seems likely. They should be available from any good nursery, but if you can't find them in your area they are also available online.

Apparently if you can develop your ground beetle and centipede populations these are natural predators. I don't know if you could get results fast enough for this season, though.
 
Paul Gurnsey
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I do have a centipede problem in my house from time to time.....I live in Korea and they actually bite people here....next time i catch one I will just go throw it in my garden. I should look into breeding them and unleashing hell on my anual noise making pests.
 
Thekla McDaniels
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Hi Paul, welcome to Permies.

That sounds pretty frustrating losing all your tomatoes.  Where are you located that you are planting tomatoes this time of year? 

There are natural predators and endemic diseases that keep  populations in check in many parts of the world.   Depending on your location, there might be innoculants available that are approved for local use. 

Bird and small mammals like moles and squirrels eat the large juicy grubs,  you could also eat them.  Deep fried is most usual.

Are the grubs eating the roots? or sucking the sap?  Could you get some photographs the grubs and post them?  Especially I am interested in the mouth parts, because they will either be for sucking or chewing.  And photograph destroyed root systems and post them too, to give us a better idea what kind of damage you have to deal with?

Are you in  a moist climate?  Some species of cicada larvae build aeration towers up out of their burrows, which seems like would make them very easy to find.

I am very curious about this situation.  I have never lived where there are cicadas, so I have never faced this situation.  I'm interested in seeing what gets posted by all the farmers and gardeners in the cicada rich parts of the world.
 
Paul Gurnsey
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I am sure they are eating the roots and also sure they are cicadas. I have a nice healthy plant one day and the next it is fallen over green but soon to be dead. Here in Korea it is an anual cicada cycle. Every year I hear their songs....and while I do like hearing it....i like  eating my veggies better.
 
David Livingston
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Hi Paul
You are in Korea one assumes Seoul( http://www.holiday-weather.com/seoul/averages/october/) and your tomatos have died ?  I looked at the average temperature  and to be honest I am not surprised as most Tomatoes dont cope well when it gets too cool
Is this a possible answer rather than insect damage ? Cool over night temps will flatten them too
David
 
R Ranson
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It's really difficult when we aren't right there to see the damage.  Is it possible to post some photos?

There are lots of times when I put loads of effort into solving one problem, only to discover it wasn't the problem, to begin with.  I think that's why we are so interested to discover more about these grubs.  Some grubs do cause damage, and yet, what you describe is different than what I've seen.

In permaculture, the trend is to observe first - there are so many things that could be causing these symptoms, grubs are just one of them, or they could be a coincidence or a symptom of a larger problem.  It would be sad to waste time and effort fixing the grubs only to discover they were actually helping solve a bigger problem.  Maybe the roots are suffocating due to poor drainage and the grubs were aerating the soil. 

It's like cholesterol in humans.  For years we thought cholesterol was the cause of heart disease when now we know it's something the body creates as an attempt to repair some damage.  And yet popular opinion continues to believe that dietary cholesterol causes heart problems.  Could it be these grubs are a symptom and local lore says they are the cause? 

But like I said, I'm not there so it's difficult to see first hand.  Photos will help, but in the meantime, let's assume these bugs are causing the problem.  What are the solutions?

Someone mentioned predatory insects are useful.  They often are expensive to buy, but you mentioned you find them from time to time in the house.  What you could do is to put them in a jar with some soil and the grubs and see if they kill the grubs.  If so, then add them to the soil.  It might not be the best idea to add them directly without an experiment in case they aren't the right grubs/insects but just look like them.

Drainage has a huge influence on grub activity.  If your soil is too moist or compact, can you create a raised bed kind of thing for next season?

Speaking about season, one of the keys to avoiding bugs is to know their active seasons - March fly where I am, are most active in the rainy season - they are also attracted to vegetable material on the surface of the soil - so I don't use mulch in the rainy season.  Sometimes the solution is as simple as that.


In case you want to go further into identifying the grubs, have a look at the March Fly Solution thread.  It shows how I grew some grubs into adults and sent photos to the bugguide people.   They usually give me a positive identification within about 4 minutes - FOR FREE!  I love those guys! 
 
Thekla McDaniels
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Two possible strategies: 

1.  change the conditions to make it harder for grubs to survive,
2.  support the development of a population of grub eaters.

If moisture in the soil is making life easier on the grubs, one thing to consider is raising the level of the beds where you are losing too many plants to grubs.  What do I mean by "too many"?  Well at a low level population, you lose a plant here and there, and what you get in return is a population of creatures who eat grubs, and once they get established, then they keep the grub population in check.

If the cicadas are native to the area, there are cicada larva eaters.  Figure out who they are and which would be easiest to host in your garden space.

Here in the desert, with gravity flow irrigation, because there is no rain during key parts of the year, I do the opposite.  I plant the plants lower in the soil, so they can have their roots down in the layer where life is happening in abundance.  I keep  the top layer of the soil dry, there is less evaporation from the surface of the soil and because of the dryer conditions I have fewer aphids, no slugs no snails.  Just an example of making adverse growing conditions to discourage creatures that are not contributing to my goals.

With regard to populations of predatory creatures, it does take awhile for things to stabilize.  I've had a grasshopper problem for several years.  Grasshoppers are migratory, so even if all today's resident grasshoppers were gone today, there would be more tomorrow.  To make matters more challenging grasshoppers are affected by temperature and level of moisture in the winter  and spring, and I never can remember which particular combination gets the plague levels, but the grasshoppers take care of that.  They come when conditions are right for them.  I used to keep guinea fowl, and they kept the grasshopper population down, and they ate more of other insects and more bought feed when there weren't so many grasshoppers.  I had to get rid of the guineas, and the grasshoppers had another population explosion.   This year I had thousands of "hatchling" toads.  I think they were feeding on the tiny grasshoppers.  Next year with so many toads, I think the grasshoppers will have a hard time reaching plague levels.  They have to go through several very tiny instars, just right for new hatchling toads, and small toads, and as the season progresses, the toads will be bigger, able to eat the larger grasshoppers resident and incoming.  The way I imagine it, I'm raising an army of grasshopper eaters.  As long as the grasshoppers are more numerous than the toads can keep up with I think my population of toads will increase.  When I have the two populations at levels that balance, the numbers of grasshoppers should level out.  And the toads will not grow as fast, maybe the newly hatched ones will not survive at the same rate.

One predator one prey is over simplified.  Ideally there would be more than one food species for the predator, and there would be more than one predator on the pest.  The increase of complexity will create a more stable system, but it's easier to explain in terms of just one.

I don't know how well I did at explaining, but I hope you get the point, and that finding the predator species will not be too difficult.

With fall coming on, you'll have all winter to study and research, and hopefully when spring comes around and the soil warms up, you'll be ready!  You might have so many different things you want to try that you'll be looking forward to those grubs, so you can test all your ideas.

 
Thekla McDaniels
gardener
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Location: Grand Valley of Colorado's Western Slope
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Just had a new idea.

When trying to bring the soil back in to balance, one thing to do is cultivate populations of soil micro organisms.  I don't know why this would not also work with nematodes.  What you need to find is a healthy and balanced ecosystem that supports cicadas as one part of the mix, that has not been poisoned or sprayed, so all the other organisms are also present.  Then transplant some of that soil to your garden.  If there are predatory nematodes, a few should come along.  If there are spores of cicada diseases, some should come along.

Make a soil organism nursery for these organisms to thrive (try to replicate the conditions where you got your donor soil) right next to your garden, so that you are not disturbing your soil micro organism plot when you work in your garden, as most healthy soils prefer not to be tilled or "worked".  The micro organisms should be able to migrate out into your garden space, if there are things for them to eat and interact with.

 
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