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Good Natured: Too much of a good thing?

Published: Friday, March 21, 2014 11:38 p.m. CDT • Updated: Wednesday, April 9, 2014 2:07 p.m. CDT
Caption
(Photo provided)
Roughly the size and color of roasted marshmallows, egg cases of Chinese mantids seem to be in abundance this year. Are they too much of a good thing?

I’m sure we can all relate to the expression, “too much of a good thing.”

With St. Patrick’s Day still in recent memory, some of us may regret consuming too much corned beef and cabbage. Or green beer, as the case may be.

The excesses of Fat Tuesday aren’t too far in the past either. Can you say paczki? (For the record, I can, but only because I once worked for a bakery magazine.)

Today though, I find myself looking at a pile of things, none of which are edible and any one of which might be considered good, by itself. But together, to my eye anyway, they definitely look like too much.

I’m talking oothecae. Specifically the egg cases of Tenodera sinensis, the Chinese praying mantis.

Last week Lisa O’Brien, our school program coordinator, and I headed out on a mission. Our aim was to find “a few” Chinese mantid cases, which we would then distribute to local kindergarten classes for use in a learning unit on life cycles.

The beauty of this new program is threefold: Teachers don’t have to purchase eggs to hatch; nor do they have to figure out what to do with the little darlings once hatching occurs, since we will take the insects back. The St. Charles Park District’s natural areas also benefit, because the items we’re removing are not native.

With the sun shining and temperatures, hallelujah, above freezing, Lisa and I made our way to Timber Trails Park in St. Charles. For the past eight years, this park has been the location for our Bug Biographies program and, over that period of time, we’ve found it increasingly easy to find Chinese mantid eggs.

We had no idea, though, how quickly our quest would come to fruition.

Bam! Five minutes down the trail, we spotted our first specimen. It was a sizable creation, about the shape and color of a roasted marshmallow, affixed to a goldenrod stem that was leaning toward the path.

“Aha!” I exclaimed, and the race was on. Not that Lisa and I are competitive or anything, but from that moment forward we focused not only on finding egg cases, but on who could find the most, the fastest.

At the outset we’d hoped to find three or maybe four capsules, enough to allow each class the opportunity to observe the miracle of life – 200 or so perfectly formed baby mantids emerging from their natal sac. But 20 minutes into our adventure, we’d filled our collecting canister, coat pockets and hands, and were seeing still more cases on the stems and twigs we passed.

Just that quickly, Lisa and I went from being giddy over our success to just ever-so-slightly disturbed about the excesses we’d found.

Chinese mantids were introduced in the United States in the 1890s, as a biological alternative to insecticides. Gifted with raptorial forelimbs that feature sharp, piercing spines, these insects are extremely efficient at capturing and consuming all sorts of invertebrate prey.

On the surface this may seem like a pretty good deal – fewer chemicals, more dead bugs; it’s a win-win, right?

The disturbing part comes when you take a look at what makes up the mantids’ menu. While it’s true they prey upon the insects we have in abundance, like grasshoppers and potato beetles, they’ll also eat their share of pollinators like honeybees – creatures we have far too few of these days.

What I’m also wondering is, what effect are Chinese mantids having on our native Argiope spiders? Those handsome black-and-yellow arachnids, once prevalent in our fields and prairies, seem ever more difficult to find these days. While I’ve never witnessed a mantid-vs.-spider, Alien-vs.-Terminator-type battle, it could be that the mantids’ presence has thrown local food webs out of whack, and given an edge to the comparatively new, nonnative kids on the block.

Lisa and I visited one park, one day – nowhere near the sort of all-encompassing effort it would take to conduct a true survey of Tenodera sinensis in St. Charles. But if what we found holds true for other natural areas too, we may this summer find ourselves teeming with Tenodera.

Are they, perhaps, too much of a good thing?

• Pam Otto is the manager of nature programs and interpretive services at the Hickory Knolls Discovery Center, a facility of the St. Charles Park District. She can be reached at 630-513-4346 or potto@stcparks.org.

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