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Mud daubers - they’re one in a million

October 20, 2013
Kevin Williams - Grundy County Conservation Director , Reinbeck Courier

In all of creation, we are told that there are over 900,000 different species of insects that have been identified. Many feel that the number is closer to a million. Scientists estimate that at any one moment there are a billion insects on the Earth. Spread out evenly, that works out to 750 insects per square foot or a little over 5 per square inch.

With such an overwhelming number present here, you know that they are very important. Insects are responsible for pollinating most plants and aiding the decomposition of most plants and animals and countless others are important food for other animals. When I think about how hard we as humans have tried to control or eliminate insects, it really is extremely fortunate that we haven't found the perfect "bug killer" or we likely would have overused it to our detriment or destruction. Many people fear we've gotten too good at killing insects already. Time will tell.

That was a lengthy lead in to today's news column. The thought for the subject today came as my wife was "alerting" me to a man-killing wasp that was flying around the door with the instruction to grab the can of wasp killer. Now, we all know that it was not likely a life-threatening situation. As it turned out, it most definitely was not because the wasp was a member of the mud dauber family.

These are probably the most docile of wasps and difficult to provoke enough to sting you. I did some research into this interesting group of wasps to see how many species there are here and a bit of their life history. I found them fascinating and their story is worth sharing.

Iowa has three species of wasps known as mud daubers. They include the larger black organ pipe mud dauber, the black and yellow mud dauber, and the blue mud dauber. The latter is a beautiful metallic blue and happens to be the one that was flying around our doorway. They are all solitary as opposed to the more familiar colonial paper wasps that sometimes make nests under our eves. They have stingers but they don't aggressively defend their nests. People are seldom stung by mud daubers. Their stingers are used primarily to anesthetize their prey which is usually small spiders. Spiders are typically caught as they rush out thinking the wasp is prey caught in their web. The hunter thus becomes the hunted. The live, but paralyzed, prey is placed into mud nest chambers where it becomes food for larval wasps. I found it interesting that the adult wasps feed only on flower nectar.

Each chamber receives a single egg. The larva that hatch consume the spiders before becoming a pupa. Although two generations may emerge in a summer, no adults survive the winter. They over winter as pupa in their mud nests.

Organ pipe mud daubers build nests that are typically vertical, side-by-side mud tubes on a sheltered wall. They get their name because the tubes resemble organ pipes. Black and yellow mud daubers build layered nests of mud tubes that may be smoothed over on the outside in somewhat the shape and size of a lemon. Blue mud daubers are the least industrious of all and don't build their own nests. Instead, they remodel the old nests of the other mud daubers. Extremely efficient use of time and energy.

As you go about preparations for winter or during your cleaning next spring, should you encounter a mud dauber nest, think about their life history before you choose to knock it down and smash it.



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