Raising Mantids … or Maybe Not

We were standing at the cash counter at Baltimore Valley Nursery when something caught my eye. There appeared to be a tiny little bug climbing up the back of the cash register. I watched it intently until the lady behind the counter followed my eyes and casually said “Oh yes, those are praying mantises”. The word “those” caused me to look closer and I noticed a small sac that looked like a dried mound of foam covered in minute little perfect copies of adult mantids. It was just sitting on the counter and those things were crawling all over it. That nursery is rather open to the outside world so they would eventually find their way outside.

They were European mantises, which are invasive by accident or intent (no one’s sure which) . Either way, they’ve since become naturalized over the last century. The other one you might see in our area is the Chinese mantis (obviously introduced as well). The only indigenous species in Canada is the ground mantis, which is found in BC alone. Theoretically, you should be able to find their egg sacs in the wild if you walk in the Winter. However the wife and I do walk through the Winter and we do well to spot huge cecropia moth cocoons much less little dried foam sacs (properly called ootheca). So if you wanna watch up to 200 mantises emerging from their sac, or populate your garden with them you could check online or at your local nursery.

I began this write-up in preparation for a story about these critters as, we were going to buy an ootheca this Spring. Then I started to think of the few times I’d seen mantids, and what they were doing, or more importantly, where I saw them.  With a few exceptions, they were mostly spotted on the flowering parts of plants. I thought they’d be chowing down on grasshoppers eating the plant’s leaves. So, I researched my subject and found … though mantises are touted as insect pest controllers, that reputation is debatable. Be advised that they don’t differentiate between pests and beneficial insects. They’ll chow down on bees and butterflies with the same ferocity as they will grasshoppers. So keep that in mind before you purchase and release a coupla hundred potential pollinator killers into your garden. I certainly have. Also remember, you will be contributing to the propagation of an invasive species.

This guy ain’t waiting for no grasshopper

The sites which sell the egg cases online assure you the insects will clean up all the bad bugs in your garden, then move on. The actual fact is, as long as there’s something to eat, they won’t be going anywhere. I understand that the egg cases can be sold commercially as they’re considered a better solution than chemistry since chemistry is a non-discriminatory killer (and mantids aren’t ?).  I suspect it’s more a case of, they’ve become naturalized and are here to stay so why even try ? While perusing Gardenweb.com (the gardening forum), I read that many contributors said they found their buddleia (butterfly bush) crawling with well camouflaged mantids. So they obviously know where to wait in hiding.  I’ll have to keep an eye on our two Buddleia this year.

And that ain’t no grasshopper

What concerns me more than European mantids eating butterflies and bees, is that the Chinese mantis has been observed consuming Monarch butterfly larvae. Chinese mantises are sold as pets. Most prospective owners just buy the ootheca, keep a few as pets, and release the remaining coupla hundred siblings, thinking they’re doing a good thing. This comes as, on Dec 5th 2016 the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) changed the Monarch butterfly designation from “special concern” to “endangered ”. Monarch butterflies have finally achieved endangered species designation. Ain’t that grand, or did you think they already were designated ?

Of course, trying to reverse the situation will involve cooperation between three countries, but  promoting the rearing and releasing of hundreds of mantids isn’t gonna help any. Particularly since they will all kill Monarch adults, and now we know the Chinese mantis will feed on the larvae as well.

I figure, anything big enough to interest an adult mantis (between 2 & 5 inches long, depending upon species) is gonna be easily visible to you. So, why not just pick it off and stomp on it ? The bugs that cause the majority of gardener’s woes, are miniscule, virtually impossible to see until they’ve established a population. The tiny bugs, logically, need tiny predators. That would be ladybugs and green lace wings, also available in Nurseries and on line. So, I guess I won’t be raising mantises this Spring, but that’s OK ‘cause I got another idea. I often thought It’d be fun to see what a wetland looks like “cross-sectionally”. So, the wife got me this:


I’m gonna dump a shovelful of swamp muck and a liter or so of water from the same pond, into my tube. Then I’ll sit it on my back deck and watch what happens in it over the season. I’ll let you know if anything interesting occurs.


Ps – if I don’t recommend raising Mantids,  where did I get the great photos ? They are compliments of Pixabay.com the CCO public domain free for use repository. Though attribution is not required, the photographers responsible for these fantastic shots are :





  1. Anonymous · · Reply

    Damn shame about them eating the monarch larvae. Only saw two Monarchs last year. Guess I was lucky. I am so tired of our animals/insects/critters either heading towards or on the endangered listings..but worst is when we are told…they are now extinct. Can’t tell you how much that upsets me.


    1. I thought I couldn’t imagine a World without monarchs. Now I’m seriously beginning to wonder which will be gone first, them or me.


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