Creating a wildlife haven one plant at a time

Monday, January 7, 2013

Alien vs. Native Ootheca

As gardeners, we are very familiar with the debate of native versus invasive when it comes to plants but what about insects. There are many  introduced insects some intentional and some by way of imported goods or accidental escapes. Kudzu bugs, Japanese beetles, Asian lady beetles, hemlock wooly adelgid, Africanized honeybees are a few that come to mind. We battle these constantly. But how do these introduced species impact the native populations of insects?

Recently I found some egg cases in our garden that were identified as the native Carolina Praying Mantis (Stagmomantis carolina) thanks to Janet at The Queen of Seaford and Clare at Curbstone Valley.

egg sack from Carolina Mantid

Female mantids lay their eggs in a case formed from a liquid foam secreted from the abdominal glands. The foam quickly hardens creating a protective shell. To see a YouTube video of a Carolina Mantid laying her ootheca click here.

In North America all adult mantids die in the winter. The eggs that overwinter in these cases are the next generation that will hatch in spring. I didn't recognize these initially as an ootheca because they are different from those that I normally see in our garden.

egg sack from Chinese Mantid
These are the egg cases from the Chinese Mantid (Tenodera aridifolia). They are significantly larger than the native cases.

There are twenty native mantis in the United States. Most of them are small and brown. The big, green mantis that I often see are from China, imported in the 1890's to work as biological control agents and eat pest insects. Unfortunately, they often eat the smaller native species of mantis contributing to their population decline.


I am thrilled to have the native species in my garden. Hopefully they will manage to co-exist with their Chinese relative or better yet thrive because I don't seen any way of getting rid of the alien insects. Have I become an insect snob? I would love to hear your thoughts and experiences on dealing with aliens.

19 comments:

  1. I had no idea that you could tell based on the egg sack. I will pay more attention now - I definitely have found the Chinese ones in my garden. Now I need to look harder to see if I can find the Carolina ones too. That egg case does look familiar ...

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  2. Until now I had never known that the larger mantids are a species from China. I'm glad you've enlightened me because I've noticed, the past couple of years, very small ones that I just figured were 'babies'. Of course that doesn't make sense for an insect. I've been growing more and more native plants so I hope I'm giving them a nice place to stay. I'll pay more attention now. Thanks, again.

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  3. Mantis also eat hummingbirds. I have removed two off of my hummingbird feeders since moving to SC. Great info Karin.

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    1. It is hard to believe that a mantis could eat a hummingbird and heartbreaking. I wonder if the Chinese mantis, being larger, would be the species to go after birds and mammals or does it make a difference? Do you remember if the two you removed from the feeders were native or alien? I will definitely keep an eye on my feeders this summer.

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    2. I believe it was a Chinese mantis as it was really large.

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  4. Isn't it wonderful when you find the natives in the garden, instead of just the alien species? So glad this mantids are calling your garden home. It's difficult dealing with aggressive intruder insects without harming the others. I think the best we can do is support and encourage the native species as much as possible. I hope these eggs hatch into lots of new native mantids!

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  5. Thanks for the entomology lesson! I didn't even know there were native and alien praying mantis species.

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  6. Fascinating and I did not know the difference. i do not see any that I am aware of but will keep a keen eye this year to see if we have native ones around. What a great sign for your wildlife garden when you find the natives have come home!

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  7. I find it really surprising that a mantis can take a hummingbird. Maybe the newly hatched, but an adult? That is something to look into. We have the large green Chinese ones here too. I always view them as beneficial. Anything keeping harmful populations in check seems like a good thing in the gardens. But I know they will take just about any bug though.

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    1. Donna, here is a link with some photos of how the praying mantis does this. http://www.birdwatchersdigest.com/bwdsite/learn/hummingbirds/mantis-hummer.php#

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  8. I had no idea there were Chinese mantis! Now I wonder which one I have in my garden. Next year i'll be sure to have a closer look!

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  9. I knew the praying mantis could eat the nestlings, but I did not know they could eat the adults. Amazing! I realize we must live with all of this, so I try as best as I can. I do take steps with natural methods against Japanese Beetles because they can be so devastating to my garden. Very informative and interesting post. BTW...happy new year!

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  10. Fascinating! I know very little about mantids, so your post was very helpful. I've always found them to be fascinating creatures, but I'm shocked to find out that the large ones will actually eat hummingbirds. Wow!

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  11. I haven't seen a mantis in my garden in a while but I also haven't been looking. I never knew the big green ones were a Chinese variety. I think I'll buy some egg cases this year. :o) Actually, I think I'll go looking for egg cases in the shrubs, too. I'll be sure to do it fully clothed. :o)

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  12. Definitely not an insect snob! Native insects are just as important as native plants. I participate in the Lost Ladybug Project which is trying to gather information about how non-native ladybugs have infiltrated north america. When I first became involved I was shocked to find that almost all the ladybugs I see in my yard aren't native to north america at all. We are slowly changing our environments and its not necessarily a good thing.

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    1. I agree Marguerite. I sometimes wonder why the "experts" think it is a good idea to introduce species to solve "pest" issues before the impact is really evaluated properly. I think most people would be surprised that the ladybugs we see most of the time are not native. What an interesting project you participate in.

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  13. Hi Karin, your mantis ootheca looks so different than ours, that Chinese one is also different. Ours is roundish, smaller and white. We have lots of mantis in our property, but i confess i haven't seen a female doing that nor the eggs hatching. I guess i need more time poking under those leaves. Now, you are challenging me if our mantis are native or foreigner! haha.

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    1. There are so many species of mantis; I would guess that your native species is different than ours. It is interesting that their ootheca are all so different.

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  14. I have seen the green, nonnative 'praying mantis' in my garden from time to time. I will need to keep my eye out for native mantis. The addition of any beneficial insects to my garden is welcome.

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