March Fly Solution?

If decimated means reduced by one tenth, what would be the word for reduce by two thirds?

That's the problem I'm having with my poor fava beans right now. Whenever I dug around a failing fava, I found these great clusters of bug larvae happily munching away on the roots.

I brought a bunch of maggot infested soil, as well as an almost dead fava plant, and hatched the larvae in my bug house. Bughouse being a clear plastic bin with a bug screen duct taped to a whole in the lid. The larvae got all lethargic and I thought I had killed them, but instead, they hatched(?) today. The people at BugGuide.Net thought it might be March Fly. From my limited insect identification skills and google's help, I think they might be on to something.


What is a responsible farmer to do?

My goals on the farm are to work with nature to find solutions. Ideally I would like to find an organic solution. Failing that, one that avoids soy and petroleum based products is a must.

My options as I see them:
- let nature take it's course and if any of my beans survive, I save their seeds as a selection for bug tolerance. It looks like they are skipping every third plant as they make their way through my bean patch.
- Exterminate every stinking last bug somehow, even at the risk of killing earthworms and other beneficial beasties (I don't like this option).
- Sacrifice my fava beans and run the chickens in a chicken tractor where the infestation is heaviest... note the infestation is throughout the garden, but is having the strongest effect on my fava beans... also note, this is the last of my seed of this variety since it didn't survive last winter. The ones that are surviving the bugs are doing exceptionally well for favas in our location at this time of year.
- Don't grow any vegetables this year, and transform the entire garden into a chicken run until the bugs are gone.

- Some better solution that the smart people who hang out at Permies recommend.

Anyone dealt with these bugs before?
I'll consider any idea, even daft ones.

And, yes, I've already spent a few hours sifting through soil picking out every bug. I got through 2 cubic feet of soil before giving up, there are so many grubs.

Learn as much as you can about these flies. Maybe there's a clue there.

Having all the beans in the same place helps the pests. At least move some to other places, single plants surrounded by things the bugs aren't bothering.

Desperate to save at least one plant for seed? You cleaned some soil. Use that in a planter or buy some soil.

Thanks Roy, great advice.

I don't think I'll go to heroic effort to save these favas, as I'm not completely in love with it as a food, yet. Thankfully the bugs haven't found my medieval variety of favas, so fingers crossed I'll get a nice harvest off them. They are the ones I'm most keen to try.


The thing I've learned about March Flies is that they like organic matter like leaf litter, twigs, manure when seeking out somewhere to lay their eggs.

Where the most clusters are located in my garden (prior to them migrating to the favas) was where I had used chipper mulch on the path ways, and even more so, where I put a mulch of straw bedding from the llamas around the plants.

Yet again, mulch fails me. As much as I enjoy reading about everyone's successes with mulch, I fear that it is the one constant for my garden failures. We just don't have the right climate for mulch. Wrong bugs for a start. This is especially true in winter when one would expect mulch to save us from any sudden ground frosts. Mulch seems to prevent the tiny rainfall we get during the growing season from entering the soil, the dew that we get each morning will settle into uncovered soil, but under the mulch is always dry. Maybe it's like Carol Deppe says in her book The Resilient Gardener, mulch just doesn't work in this part of the world.

The only place mulch hasn't caused me grief is in the permaculture herb garden.


I removed the mulch from the remaining garden, and fingers crossed it will make my garden less attractive to the next generation of bugs.

While I was doing this, I sat my favourite old hen in front of the favas. She went right to work scratching in the dirt and gobbling up the grubs. They are far more delicious than even earthworms. I think, two or four chickens for a supervised hour or so a day should be enough to bring the bug population down to a dull roar instead of a raging tide. Not all chickens like the grubs, so I'll have to experiment and see which ones are especially focused on grub munching.

Muscovy ducks don't like the grubs at all.



The only thing the grubs aren't bothering yet is the garlic and the well established kale (giant jersey). Maybe next winter, I should only grow garlic and kale?

The chard has been hit hard by everything this winter, frost, heat, wet, dry, a thousand and twelve leafhoppers, and now the March Fly grubs. I don't think this variety is worth saving for seed, at least not from this seed source. Going to be on the look out for new chard variety next fall... or perhaps work on my dream of a tender salad green mangelwurzel. Either way, these March Flies are the final nail in the coffin for this line of chard in my garden.


There is some suggestion that March Flies are pollinators, especially for fruit trees. I don't know if that's everywhere in the world, or just some spots. But interesting. Now I know what they look like, I will keep an eye out for them.

I'll let you guys know if there are any more developments. Would still love to hear from anyone who's had similar expierences. What did you do?

No experience with these flies giving you trouble, however . . . . regarding ducks and chickens as grub cleaners I do have a thought or two.

I know if you introduce the larvae to young duckings, and take ducklings into the garden with you while you scratch up the grubs they will learn to find, eat and enjoy them. Then after they are grown they can be used to teach the next generation.

We always had a couple ducks following us in the garden and flower beds. They had learned that when we garden they find easy meals. So they would search the base of every plant and bit of dirt moved. We had to be careful not to shovel them a time or two as they had no fear of us or our movements when easy food was at hand. I thought to myself - this animal is great! Then I had a couple full grown ducks given to me. They just watched us from a distance, and would only come up if they saw the feed bucket. If I wasn't tossing them feed they recognized they would turn around and leave. Even throwing them earth worms didn't work. They didn't seem to know what they were, and took it as an act of hostility. With our raised ducks all I had to do was point to a bug in the dirt and they were on it!

For myself I don't like to use chickens if I can help it. A loose chicken can ruin hours of landscaping work in just minutes if one isn't careful.
As for ducks - there is one issue to plan for if using them in gardens, and that is their blind spots due to eyes on the sides of their heads. Your new plants will need protection. Plants protected with something high enough that the ducks can see it (chest level or higher). Will keep ducks from walking over and breaking stems until the plants are big enough that the duck has to walk around and not over. I use welded wire, cut so it has spikes on the end I stick in the ground. Or I've used bamboo sticks, pots and other garden decor to block off emerging plants in the spring. Once the plants are established remove the protection.

Remember the Chinese using cormorant ducks to fish for them - well turns out most breeds of duck are very trainable.
I prefer Indian Runners as 'lawn & garden ducks' because they are great forgers, with smaller bodies that fit around plants much better than meat-size ducks, and they are not as rough on plants. They come when you call and so you can - call them into the garden and then out again easily. They don't fly away like other light breeds, but prefer to walk. I wouldn't leave full time access to the garden, just a few minutes daily while you are doing your garden upkeep. They will quickly learn the routine of helping you in the garden.

I know this doesn't help you now, and I'm sorry. But maybe some animal training can come from your lost crops for this year and help you in the years to come.

Good thought about the ducklings. They certainly do better when trained on what to eat. Next time I might try some of these runner ducks. The muscovies are great hunters, very self sufficient, but they happily trample any plant that gets in their way, the more valuable the more complete the destruction.

This experience is definitely inspiring me to train some baby critters - maybe next year I'll plant my winter crop in all tall kale and use it as training ground. The kale should help provide shelter from the sky-monsters (bird talk for eagles, ravens, hawks) and still be tall enough the baby birds won't completely destroy the crop. But then... I won't know where to grow my garlic. Sigh. Garden planning is hard work. I much prefer digging.


Thankfully my old hen isn't like a regular manic chicken. She sits where you put her, waits for me to turn over a forkload of soil, eats the grubs that turn up, maybe scratches a bit if I didn't reveal the grubs properly, then waits patiently for the next forkload. She's one of the more intelligent chickens we've ever had and has over 90% accuracy at predicting earthquakes. Definitely my favorite critter on the farm.

How certain are you that these larvae were part of the cause of the fava's downfall rather than a result of it?

Everything I've read on these things is that their primary food is dead plant matter.

Kyrt Ryder wrote:How certain are you that these larvae were part of the cause of the fava's downfall rather than a result of it?

Everything I've read on these things is that their primary food is dead plant matter.

That's an interesting point.

How certain am I? Looking back, I feel that there is a very strong correlation, strong enough to say probably casual relationship. I'm never 100% certain what's going on beneath the soil, as I feel that the life of growing things is infinitely more complex than humans are capable of understanding. Our mind divides things into easy to evaluate parts, which leaves a massive blind spot to greater relationships that might have influence on what we are trying to understand (basically, you're right, things can be more complex than they first appear).


Why I think the March Fly had a bad effect on the fava beans:

I hadn't mulched favas before, and I've never had trouble with these grubs before.

The other favas that I didn't mulch showed no signs of damage or stunted growth.

Digging arround the healthy favas, shows no sings of the grubs

Not mulching this year has again shown no evidence of stunted growth in any plants and no evidence of bugs in the soil around the plants. I'm growing a good deal more plants this year than last, most of them from the seed that had the problem last year (from the same batch as I planted as well as the seeds saved)

The entomologist and naturalists I consulted agreed that the bug was eating the plants roots

So correlation is definitely there.

My guess (and it is a guess) is that the bugs were attracted to the mulch and laid their eggs in it. Then, as the larvae grew, they decided that some of the fava plants had yummy roots.

Last winter they were primarily in areas that had mulch, or had been mulched earlier in the fall. They were less prevalent in areas with no mulch. This year, they are only in areas with mulch or haylage on the surface of the soil, and no where else I've dug.


The more I experiment with mulch, the more I feel there are problems with it. I've tried a lot of different kinds of mulch, but had limited successes. I think our winters are just too wet here, and our summers too dry... I seem to have exactly the same issues as Carol Deppe in her book The Resilient Gardener. It makes sense as we have very similar growing seasons. There are some situations where mulch is a godsend, and I use it gratefully there, but in my veggie garden... I'm still doing trials.

I'm a big fan of The Resilient Gardener as well [having read it twice when I almost never re-read anything.] Deppe makes some good points to be sure.

As to March Flies, you might find This Article of use. Unfortunately part of it is locked behind a pay gate [or through affiliation with various institutions.] I've contacted the researchers requesting access to it as a private gardener, but who knows if they'll even see my request let alone grant it.

According to that study, the roots of live plants are sometimes attacked, but primarily when the plant is already stressed.

It DOES state that the chance of attack goes up when organic matter is near the plants at the time when eggs are laid, but it strikes me that healthy plants shouldn't attract attack.

Lastly, these larvae are known for doing a lot of work in converting organic matter into humus so a certain population is a good thing.

My personal suggestion [if you have the space] is to continue trialing beds with and without mulch and continue observing. I certainly intend to.

EDIT: lastly, the primary habitat for March Fly larvae is grasslands, thus hay mulch is probably a great deal more attractive to them than woodchip mulch or leaf mulch.

Neat link. I'll see if my local library subscribes to it. I know they get quite a few scholarly journals.

Kyrt Ryder wrote:
According to that study, the roots of live plants are sometimes attacked, but primarily when the plant is already stressed.

That makes sense.

So, the plants with the mulch are stressed thats why the bugs are eating those plants and not the unmulched ones? The mulch does tend to hold a lot more water in the soil in the winter, which might suffocate the roots, thus stressing the plant.

The plants that had purple in them, purple tinge to flower and stem, had the most trouble... so maybe they were stressed by the mulch and the others not?

Maybe this strain of march fly, really likes fava bean roots?

So many variables. I doubt we will ever know exactly which did what.



Since space is limited, and I'm satisfied with my fava harvest sans mulch, I'm going to move onto testing other crops with mulch.

I think for me, mulch is excellent in no-till situations. Parts of the garden that emulate nature and places where I'm working with Fukuoka style philosophy. For the areas I dig, I find digging the organic matter into the soil, in a trench style, seems to create fewer losses due to bug or disease. Since it's harvest, trench in compost, rake over soil, plant, there is very little time that the soil is exposed. It seems to work really well in this clime.

If I ever work fava beans into my no-till crop rotations, I'll give another go with mulching them.

R Ranson wrote:I think for me, mulch is excellent in no-till situations.

I strive to be no-till to minimal till in all of my gardening to the best of my ability. Sometimes it's fastest and easiest to carve open a narrow trench [3-4 inches wide at most] for seeding and smooth it back down, but does that *really* qualify as tilling?

Disclaimer: my gardening experience is primarily on a silty sandy loam with very little clay. 'Drowned roots' is a problem that pretty much only happens in standing water in my soil, if the water infiltrates at all the bulk of it usually migrates quite deep.

EDIT: as to the concern over suffocated roots, winter crops like this seem like the one scenario in our climate where raised beds really make a lot of sense. They can reach down into the wet soil as needed without being drowned.

An update on these critters.

They are still in the soil, but nowhere near as bad as when I was using mulch in the winter.  They also have less impact since I've been selecting for resistance.  I save the seeds from the most prolific plants with a special focus on ones that were exposed to the grubs.  

It's a bit like Fukuoka's idea where he says "what can I not do" - by not mulching it's one less thing I have to do in the garden each year and it gives me a much better harvest.  Nice.