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Beneficial Predatory Insects

by Dawn
ladybug on grass blade

Various predatory and parasitoid insects that will benefit your garden

Predatory insects. Parasitoid wasps. Carnivorous, even cannibalistic, bugs. Sounds like something out of a horror movie, right? Actually, they’re all right there in your garden!

Now don’t go hiding in a closet and refusing to go outside again. Most of these critters have absolutely no interest in you. Even the ones that do don’t want to eat you, they’re just curious, I promise.

There are so many parasitoid or predatory insects that I can’t possibly cover them all, but I want to talk about a few with you. That way, when you see them in your garden, you won’t either (a) run screaming or (b) squish them. Neither is really a desirable reaction.

This post is going to be dedicated to educating you about the critters themselves, with future posts discussing how to attract them to your garden. So, without further ado, predatory and parasitoid insects…..

closeup of bumblebee on flower
Nope, not a predatory insect. Most of them aren’t this cute and fuzzy.

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Well, OK, these guys ARE cute, almost as cute as that bumblebee. And for my European friends, you might prefer to call them lady beetles or ladybirds. My Turkish friends would call them ugur bocegi, literally, good luck bugs.

Ironically, although probably the cutest of all the critters I’ll be talking about today, ladybugs are quicker to bite humans than most of the others. Their bite isn’t a big deal and isn’t venomous, but it does hurt a little.

ladybug on flower

I’m sure you’re familiar with the typical ladybug, bright red with black spots, but there are quite a few variations, some without spots and some of varying colors. If you don’t believe me, check out the vast array of ladybugs here. I’ve seen several of these in my garden without realizing they were related to the typical ladybug. Cool!

What do ladybugs eat?

Ladybugs are voracious little critters. You may already know they eat aphids, as that seems to be what they’re famous for. But, various species also eat scale bugs (and they can have those! Have you read my post on Houseplant Pests? I HATE scale!), along with mites, the European corn borer and other caterpillars. The adults will also eat pollen and nectar.

Ladybugs are related to the Mexican bean beetle, an important agricultural pest, but ladybugs themselves aren’t detrimental to our food crops.

“Reflex bleeding”

Fun fact about ladybugs I didn’t know until I did some research: Have you ever picked up a ladybug and had it “pee” on your hand? That’s what I assumed was happening when there would be a tiny drop of colored fluid in my hand after the ladybug left. Nope, not pee. It’s actually a toxin the bug releases through joints in its exoskeleton for protection from predators. Don’t worry, it’s not toxic to humans.

ladybug on grass

Ladybug Larvae

I do want to send you to a link to a picture of a ladybug larva before I close out the section on ladybugs. You see, the larvae are actually bigger than the bugs and rather scary and/or strange-looking, so I don’t want you squishing any thinking they’re the bad guys. Here’s a really good picture of one. Like I said, the stuff of nightmares, especially in extreme closeup, but these are the good guys, I promise!

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Eastern Cicada Killer Wasp (Sphecius speciosus)

They’re awfully big…….

Cicada killer wasps are, admittedly, really scary-looking.

cicada killer wasp

I saw a type of cicada killer wasp at the Missouri Botanical Garden a few years back (a place I HIGHLY recommend you visit if you can) and I have to admit, the wasps were intimidating. I had never seen such large wasps before and, as it was mating season, they were quite active. I’ve also seen them here in my garden, but the eastern variety doesn’t seem to be quite so big.

They can be up to 2″ long, which is a formidable size for a stinging insect. BUTTTT, the good news is, they don’t sting! Well, the males don’t sting at all as they don’t have stingers, and the females won’t sting unless you actively injure them. As they’re solitary wasps, even if one should happen to sting you (and you probably deserved it!), that will be it, they don’t travel in swarms.

The thing with the males is, they’re kinda horny little devils and they’ll investigate just about anything, including humans, to see if they happen to be females to mate with (apparently their eyesight isn’t very good!). What you may mistake for aggression is actually just curiosity.

This is much like you’ll notice in the spring when carpenter bees hover in front of your face like they’re going to murder you, when they’re actually just checking to see what you are.

As you may guess, they eat…..yup, cicadas

Cicada killers are so big because the females stun cicadas, then fly with them to their nests to feed their young. As the cicadas are often twice as big as the wasps, you can imagine this is a difficult proposition. Here’s a news article with some great pictures of cicada killers.

Praying Mantids (or mantises, if you prefer)

I think praying mantids are my favorite predatory insect in the garden. There’s just something about them that’s so engaging, especially when they tilt their little heads to stare at you. I don’t know, I guess I’m weird.

praying mantis closeup
I mean, who wouldn’t love that face?

What mantises eat

I guess, really, the question is, what don’t they eat? Young mantids will eat leafhoppers, aphids, each other (hmmm…..) and flies. Once they get bigger, moths, crickets and grasshoppers get added to the menu.

They’re also been known to eat small tree frogs, mice and hummingbirds. EEP!!!! Good thing these guys aren’t aggressive to humans! I would suggest, however, if you happen to see one hanging out on your hummingbird feeder, that you relocate him elsewhere. As much as I like mantids, I don’t want them eating any hummingbirds.

And, yes, you can handle them (gently). Although they can bite, they’re not quick to do so, and their bite isn’t venomous. I’ve handled quite a few over the years without mishap. In fact, I’ve been bitten by more ladybugs than mantises.

Male mantids get a raw deal

It’s commonly known that female mantids will often bite the heads off their male partners during or just after sex. I guess it’s a bit hazardous to be a male mantid! Although, some studies have shown that only about 1/3 of mantises in the wild actually do this. Still, a 1 in 3 chance of getting your head bitten off after sex? All right, I’m just gonna leave that one right here and move on.

Cool mantis fact

According to www.pests.org, mantises have a hollow area in their body which allows them to “hear” bats flying close by. Because bats are the mantids’ most feared enemy, this allows them to avoid potentially fatal encounters.

praying mantis
Found this guy hanging upside down on my front window one evening.
Maybe he wanted to know what we were having for dinner

Raising praying mantises

About 10 years ago, I purchased a praying mantis egg case and hatched and released the baby mantises into my yard. It was extremely cool and I highly recommend it, especially if you have kids.

Some words of caution: Mantids are quite territorial, so one egg case per average-sized yard is sufficient. Second, mantids are cannibalistic as soon as they’re born. This means that you need to keep a close eye on your egg case, and when hatching starts, be sure to get it right out to your yard and open the container, assuming you’re keeping it in the house, so the young ones can escape from each other.

Last, as I mentioned, they will eat almost anything, so you need to take this into account when balancing the good they can do with the harm they may do. As I’m going to try raising monarch caterpillars this summer, I may not purchase any mantid egg cases, as mantids can prey on the caterpillars.

If you’d like to purchase egg cases, you can do so here. They suggest up to 3 cases for spaces less than 5000 square feet, although I’ve also heard, as I mentioned, that one is sufficient for that size yard. They say to suspend the egg cases outside, but I kept my case in the house until it started to hatch, then took it outside. It’s up to you. If you do suspend it outside, I would do what they suggest and place it inside a container so birds and mice can’t eat it.

Note: This is one time I wouldn’t necessarily suggest buying from Amazon as you are effectively buying live critters and you want to make sure you’re buying from a trusted source.

Braconid Wasps

What does a braconid wasp look like?

Braconid wasps are tiny, only about 1/2″ long, so you might never have gotten a really good look at one, or you might even have mistaken it for a tiny fly. There’s a good picture of one here, if you’d like to see it. Keep in mind that there are many species of braconids, so they might not all look exactly like this picture.

Prey for braconid wasps

Braconid wasps are parasitoids, meaning they’re parasites that kill their hosts. They typically lay eggs on or in their victims, and when the young hatch, they make a meal of the host.

Hosts include tomato hornworms, beetles, aphids, caterpillars of various types, stink bugs and squash bugs.

The adult wasps feed on flower nectar and pollen and particularly like herbs and plants in the carrot family (carrots obviously, but also Queen Anne’s Lace, celery, anise, dill, fennel, lovage, parsley and parsnip).

Assassin Bugs

assassin bug
Not very pretty, but very beneficial!

What assassin bugs eat

The nymphs of assassin bugs eat many kinds of caterpillars and moths, such as gypsy moths, eastern tent caterpillars, cankerworms and fall webworms.

Wheel bugs, a type of assassin bug

Wheel bugs are a type of assassin bug that’s been known to attack both Japanese beetles and brown marmorated stink bugs, so you definitely want them in your garden! My only problem is that they look a bit too much like spiders for my comfort. Still, spiders are the good guys too, so I’ll learn to deal.

Assassin bugs do bite

These guys are the one type of insect we’re talking about today that will bite fairly readily, and their bite is painful, although not poisonous. They aren’t going to come after you, but picking them up probably isn’t the best idea either.

Thread-waisted Wasp

thread-waisted wasp on flowering tree
A thread-waisted wasp in my garden

Last but not least, we come to the thread-waisted wasp. These are easily the largest wasps I’ve seen in my garden. Again, however, they’re totally nonaggressive and will only sting if you injure them.

I can attest to their total nonaggression. I’ve stood right under, almost in, the branches of the flowering tree in the pic above with these wasps (among others) buzzing all over and around me. They’ve paid absolutely no attention to me at all, and I’ve never been stung. I’ve been stung by hornets and yellow jackets, but that’s a subject for another day.

Prey for thread-waisted wasps

All species feed their larvae insects. Some nest in burrows and feed them caterpillars, while others feed their young grasshoppers, crickets or cockroaches. You may have heard of mud daubers. These are a species of thread-waisted wasp that create mud cells in the corners of eaves and feed their larvae spiders.

No matter which species you have, they’re the good guys, as are all the critters we talked about today.

These Beneficials will occasionally eat other Beneficials

One last thing I feel I should bring up before I close: Most or all of the beneficial insects we talked about will, given the right circumstances, occasionally prey on other beneficials. This doesn’t mean we should try to eradicate them from our gardens, as the good they do far outweighs the bad. When our plantings are diverse and we’re encouraging a lot of beneficial insects, we don’t necessarily need to worry about a few casualties along the way.

Posts Related to Beneficial Predatory Insects

I hope you’ve enjoyed my post today. As always, any comments or questions are greatly appreciated. The images below are pinnable and I’d love a few pins if you have appropriate boards.

Smile and have a crazy organic day!

beneficial wasp on flower
ladybug, a beneficial predatory insect

Various predatory and parasitoid insects that will benefit your garden

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Sarita 04/13/2019 - 4:21 pm

This was so interesting! What violent bunch, lol. Love the idea of the praying mantis cases – I”m going to see if I can order any from a Canadian supplier as this would be an awesome homeschool lesson!

Dawn 04/13/2019 - 11:13 pm

That would be amazing for your kids! They’re really fun!

Dawn 04/13/2019 - 11:14 pm

Glad it was helpful! Let me know if there’s anything else I can help with.

Debbie 04/09/2019 - 8:35 am

Love this article! We had a conversation at my house earlier this morning about “why anyone would want to attract ladybugs predatory wasps.” Great information! Glad you are raising awareness of the misunderstood “good guys!”

Dawn 04/09/2019 - 9:28 am

Glad you liked it! I’m actually fascinated by wasps and bees, they’re such interesting creatures, and for the most part, they aren’t interested in harming us, as long as we leave them to do what they want to do. I do have this weird thing: I like to pet bumblebees. I talked about it in a past post (although I can’t remember which one), and I know some people thought I was crazy, but it’s really fun. As long as you’re not allergic to them of course, wait until they’re busy on a flower and VERY gently stroke down their backs. They often will flick a foot up and kind of hit your finger like “what are you doing to me?”, but it’s still really fun and cute. I know, I’m weird, but I’m fascinated by them. I’d love to have honeybees, but haven’t convinced the hubby…..yet.

Nikki L Gwin 04/05/2019 - 11:57 am

I had NO idea what a lady bug larvae looked like! Great information here. I also had no idea that assassin bugs were useful bugs. Totally learned new stuff today!
🙂 gwingal

Dawn 04/05/2019 - 3:06 pm

Glad to hear it!

Clarissa 04/03/2019 - 8:01 pm

What a great post! Every Summer we have lots of little praying mantis babies that hang around our pool. I always move them to the shrubs. I wish I had more ladybugs and just found out last Summer what the larvae look like.

Dawn 04/04/2019 - 12:22 pm

Mantises are so cool! I just love seeing them, although we don’t have as many as I’d like.

Linda Carlson 04/03/2019 - 5:05 pm

glad to see this article.. The beneficial bugs don’t get enough publicity ..

Dawn 04/03/2019 - 7:04 pm

They really don’t, and the problem is that a lot of them look like wasps and hornets, so people are squishing them or spraying them!


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