Monday, July 28, 2014

Death Comes For the Grasshopper(s)

Not surprisingly after 3 hot, dry years, there have been a lot of grasshoppers around this summer.  Grasshoppers and hot, dry weather go together like bread goes with peanut butter and jelly.  I've been noticing a few things that bode a little better for next year, though, and I'd like to share them with you.

The beginning of the summer started with literal hordes of grasshoppers, especially newly hatched nymphs.  The photo above shows a phalanx of said nymphs on a soon-devoured broccoli leaf.  It wasn't uncommon to have hundreds of tiny grasshoppers flying up with every step through grassy areas. 

Now, towards the end of July, there are still a lot of grasshoppers, but the numbers seem to have declined a bit - dozens fly up at every step instead of hundreds.  Sometimes only a few fly up.  I haven't sprayed or made any effort to curb their numbers, so what has happened?

First of all, the weather has been cooler and wetter than during the last 3 or 4 summers.  Cooler, wetter weather is good for plants, but bad for grasshoppers.  Newly hatched grasshoppers can be killed by cool, wet weather.  Truthfully, I'm not sure we were cool enough or wet enough for this to happen this year, but I'm mentioning it anyway.  However, warm, wet weather can also have a negative effect on grasshopper populations....

During warm, wet weather, there is a naturally occurring fungus, Entomophthora grylli, which infects grasshoppers and causes them to climb to the top of vegetation and grasp the stem with their legs, then die.  I've been seeing quite a few grasshoppers seemingly mummified like this.  The best news is that, as these grasshoppers dry out, the fungal spores spread on the wind to other grasshoppers, infecting them as well.

So not only is there one less grasshopper reproducing for next year, but each one that dies like this has also potentially caused other grasshoppers in the area to die as well!  Rather nightmarish...but effective.

Predators have been playing a role in decreasing grasshopper numbers, too.  Just in my ramblings with camera in hand, I've caught shots of several wheel bugs eating grasshoppers. 

I've got a large population of wheel bugs this year;  after such an abundance of prey, I suspect I'll have an even larger population next year!

Spiders, too, eat grasshoppers.  This photo of a black and yellow garden spider eating a grasshopper was actually taken last October, but I'm sure that the spiders I'm seeing this summer are taking out quite a few grasshoppers as well.  (My garden spiders aren't this big yet, but they will be!)

Birds, not surprisingly, eat grasshoppers as well, although I haven't been lucky enough to get any photos of that happening.  Bluebirds, quail, pheasant, meadowlarks, lark sparrows, and lots of other birds are known to eat grasshoppers.

I occasionally see great golden digger wasps around the yard, as in this rather out-of-focus photo from about a week ago, hunting (in this case) on Bradbury beebalm.  If these beautiful, big wasps aren't feeding themselves with nectar and pollen on flowers, they are actively prowling for grasshoppers to sting and paralyze.  Once the grasshopper is paralyzed, the female wasp takes it back to her nests as baby food to lay her eggs on.

The long and the short of it is that grasshoppers are grazers on plants, and a lot of animals eat them.  With bison no longer freely roaming the prairie, I understand that grasshoppers are actually the primary herbivore for this important ecosystem!  Because grasshoppers are so mobile, it's hard to kill them with insecticides.  Ironically, it's much easier to kill the insects that prey on grasshoppers - so any time you spray an insecticide, even an organic one, you are probably helping to increase grasshopper populations, in the long run, by decreasing their predators.

Speaking of spraying insecticides and accidentally killing off insect predators, the last grasshopper predator I'm going to show you today fell victim to some actions Greg and I took several years ago before we knew any better.  While we didn't actually spray, we did kill enough of these predators that their population declined around our yard and gardens for a few years, so we've actually had more grasshoppers than we would have had if we hadn't tried to solve a "problem" we were sure we had.

The first summer or two that we lived and gardened here, we started our vegetable garden.  Despite the tall grass that we encouraged to grow on much of the property, we didn't see a large number of grasshoppers.  Some, yes, but not enough to cause noticeable damage.  Generally, our garden plants did superbly, although the tomatoes, in particular, attracted large numbers of black blister beetles.  A few grey blister beetles came too.  Not only were these insects a little creepy looking, but they ate the tomato leaves and made the tomato plants look really ugly.  I still harvested more tomatoes than I could possibly use and there weren't enough blister beetles to defoliate the plants, but definitely there were enough to make the plants look ratty. So I started to handpick the blister beetles, dropping them in soapy water to kill them.  Each morning I would do this, and it wasn't unusual for me to dispatch 50 or 100 each day.  It definitely lessened their populations over the course of the summer.

Even after I learned that blister beetle larvae ate grasshopper eggs, I continued to handpick the blister beetles, reasoning that I was seeing plenty of blister beetles, so it shouldn't be a problem.

In June, 2011, we came back from a trip to San Antonio to find several masses of hundreds of striped blister beetles writhing on our front lawn, presumably in an ecstasy of mating.  Our only thought was how to dispatch them as quickly as possible before they, too, started to eat the leaves of our tomatoes and other plants!  So we put soapy water in our shop vac and vacuumed most of them up.  Problem solved.

By later that same summer, I was seeing very few blister beetles...but hordes of grasshoppers.  As you may remember, the summer of 2011 was horribly hot and dry.  We had 53 days over 100 degrees F. and almost no rain.  By late July of that year, our althea had been defoliated by the grasshopper hordes.

For every adult blister beetle you see, an average of 27 grasshoppers don't get born.  What had we done?

For several years now, we've had so many grasshoppers that by early summer most of our vegetable garden is gone.  Once the grasshoppers hatch out, they devour the spinach, kale, broccoli and cauliflower within days.  Then the onion and garlic go.  The asparagus stalks become dried brown sticks with all the green gnawed off.  Over the course of the summer, all the iris leaves get whittled down to nubs.  Thankfully, 2011 was the only year our althea were entirely defoliated, but their leaves have been severely chewed each summer since then.
This year I'm finally seeing black blister beetles on the tomatoes and a few other plants again.  Mind you, I'm not seeing them in huge numbers, but they are there and they are reasonably common.  This year I'm NOT picking them off and killing them.   I'll share my tomato leaves so that, hopefully, the black blister beetle larvae will be feasting on grasshopper eggs over the winter!

The more I learn, the more I realize that I don't know very much.  A blog post I read over the weekend was talking about tangleveined flies as a grasshopper predator.  That's a new species I don't recognize, so now I want to learn more about them and see if I have any of those grasshopper predators in the yard.

There is an incredibly complex web of plants and animals that will generally keep each other in balance and keep the Earth healthy, if we leave enough of them alone to "do their thing."  We humans, though, get pretty cocksure of ourselves and start killing plants and animals off, thinking we know a lot and can surely manage better than Mother Nature does. 

We're not as smart as we think we are.

Hopefully my yard is getting back into balance a bit better again.  Ah, the gardening spirit never fails, does it?  Next year will be better.....


Anonymous said...

This is really a good post about grasshoppers. I did not realize how many other insects and even fungus can keep them under control. It has been very hot the last few years and like you said, every step and a hundred of them jump out. We have not been as hot this year, but there are still is plenty of them. I like all your photos of them being consumed. I don't have a lot of love for them either.

Gaia Gardener: said...

Donna, thank you for stopping by! I've been absolutely astounded at how many predatory insects there are!

Gardener on Sherlock Street said...

First of all, I had never heard of the fungus that gets grasshoppers. Wow. As for the blister beetles, that was totally new too. Again I learn something great from your blog. There is a balance out there. When we see tons of one insect our instinct is that it is bad. May just be nature trying to right the imbalance. So glad this year is more moderate and maybe more rain coming tonight and tomorrow!

Gaia Gardener: said...

Glad I could share something that you hadn't known before, GonSS!

I'm keeping my fingers crossed for rain - and I'm sure you are, too! This has been a much more pleasant summer than most of the last 3 or so. (Knock on wood.....)

ProfessorRoush said...

Hope you're getting rain today, Gaia. I see the radar blue and green over your area, anyway. Nice reminder about the ecology of grasshoppers!

Gaia Gardener: said...

Prof, we got a little rain, but not as much as I'd like. Sometimes it almost seems like we live in some sort of rain shadow....

Did you get any during this round?

Dee Nash said...

Interesting observations on grasshoppers. I hate, hate, hate them. I get lots here too. I did put out Nolo bait for them this year to reduce the numbers, but nothing else. It only affects grasshoppers and the occasional cricket. I have loads of wheel bugs. I'm careful not to smash them accidentally because they bite. I wear gloves mostly because of them. Also, I've seen a lot of blister beetles. Thank you for the information on them. I never knew that about blister beetles, and I wondered what else they did besides eat leaves.~~Dee

Gaia Gardener: said...

Dee, do you find that the Nolo bait has helped? I've heard about it, but no one has ever shared whether they think it's effective or not.

Despite all my wheel bugs, I've only been bitten once - when I reached down into a plant to take a long cutting and accidentally encountered a wheel bug, I guess. It stung like the devil for a couple minutes, then faded abruptly with no further effects. Not fun, but not shattering either. They are well worth the risk, in my opinion!

As far as blister beetles go, I've hand picked the black ones and not had any problem with blisters, despite their reputation. That said, I'm not handpicking them these days, hoping for help with the grasshopper hordes.

Thanks for stopping by! I enjoy reading your blog since I can relate to your challenges - we're not that far apart, as the crow flies.

Anonymous said...

I almost feel bad for the little guys with all these cards stacked against them.... almost...
The fungus is the worst though. I agree it's entirely creepy, both the death by fungus, and the mind control to climb upwards. It's a wild world out there!

Gaia Gardener: said...

Frank, Sometimes I do feel sorry for them...and then I notice something like the hundreds on the road this morning and my sympathy vanishes!

Gaia Gardener: said...

I've realized that I left out quite a few grasshopper predators that I know about already (and many more, I'm sure, that I'm not aware of). For example, coyotes eat a lot of grasshoppers, based on the body parts in their scat. I've also seen praying mantids happily chomping down. Frogs, toads, turtles, snakes.....

Melanie said...

I had not noticed those blister beetles until this year. .and a few on my tomato plants; but tons were on the potatoes. .I'm glad to know that they eat grasshopper larvae. .I agree. .that the longer we are able to fix our land closest to the original plan, the better off we will be!! My BIL used some type of fungal spore a few years ago. .I'll bet it was a marketed version of what you are talking about. .but they use pesticide like it's milk. .so in tryin to fix one problem, seems we must create many more!! Thanks for the GREAT advice!!

Gaia Gardener: said...

Thanks, Melanie. I don't know if the fungal spore that is sold is the same one that I see occurring naturally; I'm just glad that some of my grasshoppers are "passing on" without leaving any future replicas of themselves around!

Glad you're seeing some of the blister beetles - it turns out they are pretty awesome allies against grasshoppers.

I just kick myself for how many blister beetles I killed those first couple years. Even if I did kill them without resorting to an insecticide, I still managed to kill enough of them to unbalance populations in my yard, to my great dismay over the last several years. Oh, well, live and learn.