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How to promote predatory insects

LadybugOne group of wholly-positive garden invertebrates is the bugs who consume bad insects.  Spiders, centipedes, dragonflies, mantids (aka praying mantises), ambush bugs, assassin bugs, lacewings, ladybird beetles (aka ladybugs), ground beetles, true wasps, digger wasps, hoverflies, and robber flies all subsist primarily or entirely on other insects during some stage of their life cycle.

Although many of the species listed above are generalist predators, eating whatever ends up
Praying mantis eating a butterflyin front of them, all of these insects help keep pest population explosions in check.  For example, I accidentally let the beetles on my green-bean plants get out of control one summer, and soon thereafter I saw a pair of praying mantises move in to take advantage of the bounty.  Sure, the mantises might have been eating butterflies yesterday, but I consider them beneficial insects because they eat at least as many bad bugs as good.

Parasitized tomato hornworm
Another category of predators is the parasitoids.  Braconid wasps, ichneumonid wasps, chalcid wasps, and parasitic flies all lay their eggs on other insects, and unlike true parasites, the wasps and flies eventually kill their hosts.  That's great news in the garden since many of the prey insects are bad bugs, like tomato hornworms or bean beetles, so the parasitoids keep the pests under control.  As a side note, in case you're scared of the term "wasp," all of the parasitic wasps are too small to be a problem for human gardeners.

Parasitized bean beetle larvaMany gardeners fall in love with the idea of predatory and parasitic insects and decide to buy some of these critters to seed their garden.  However, I believe that you really need to encourage all of these species at the ecosystem level.  I've heard of people opening a container of expensive insects, only to have them all fly away because the garden isn't a hospitable environment for the predators to live in.

Mud dauber nest

Instead of spending your money on insects, why not spend a bit of time encouraging the good bugs you already have to stick around and reproduce?  Many depend on flowers during some stage of their life cycle, so you can encourage them just like you did native pollinators by ensuring you have copious pollen and nectar sources available throughout the growing season.

In fact, you might receive double the benefit from any nest sites you put out for your native pollinators.  Brian Cooper erected mason-bee blocks in his garden, and ended up encouraging mud daubers by providing wet mud nearby.  Brian wrote: "When we went to harvest the bees, we found mud daubers also laid eggs in some of the unused cells.  They collect food for their young inside the cell before they cap it with mud.  I found one cell that was filled with caterpillars and a dauber larvae, and another cell with a pupa of the mud dauber and just bug parts left over."


Dragonfly on Swiss chard

Immature wheel bugWeedy edges will also encourage predatory insects since the predators need to be able to find lots of insects to eat even when your garden pests are under control.  In addition, dragonflies need a pond into which they can lay their eggs, and many insects will benefit from having a very shallow body of water from which they can drink.  When attracting predatory insects, it's imperative not to use any pesticides (even organic ones) and to allow low levels of pest insects to fly under your radar.  If there aren't any bad bugs around, your predatory insects won't have anything to eat and will go somewhere else.

In fact, you'll probably sense a theme throughout Naturally Bug-Free.  To encourage the good bugs, let nature move into your garden.  Leave things alone and the beneficials will come.

I hope you enjoyed this excerpt from Naturally Bug-Free!  If so, you can download the ebook for $1.99 on Amazon by clicking the link above.  Or just wait for another excerpt tomorrow on the blog.



This post is part of our Naturally Bug-Free lunchtime series.  Read all of the entries:


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Providing habitat for insects is my favorite part of gardening. At my current location, I'm a bit more than 3 years into creating an ecological balance. I garden commercially, but never put any "organic" sprays (no neem, bT, etc.). I am absolutely seeing the benefits now. No major outbreaks as they are quickly mitigated.

My favorite helper plants: yarrow, tansy, parsley, cilantro for the little wasps and hoverflys

borage hedge as a green lacewing nursery. when you get a bunch together it has the added bonus of sounding like a beehive from all the bee activity.

radish flowers, african blue basil, tusli, chamomiles, and any allium flowers

and, surprisingly to me, the absolute best is fennel. Every day, all day the flowers are covered with the most diverse amount of species, including literally dozens of varieties of wasps at one time.

I know I'm forgetting many, but all these are great to include in the garden. Its important to have various types of flowering plants throughout the year. For me, this means letting many naturally adapted plants (weeds) flower, especially in the winter.

Comment by eric Wed Feb 12 09:37:56 2014
Eric --- Wow! Great to hear your firsthand experience! Any chance you have some photos of your farm in summer that I could include with these tips in the second edition of Naturally Bug-Free? I'm always happy to send a paper copy of your choice of book (Weekend Homesteader, Naturally Bug-Free, Watermelon Summer) to contributors, and it sounds like you've got a lot to share!
Comment by anna Wed Feb 12 10:20:17 2014

Sure,

Not sure if its what you're looking for, but my wife has a few photos on this site http://regenerationatx.tumblr.com/

I haven't been good about taking photos, or posting the ones I have taken. Email me if you are looking for something in particular.

Comment by eric Wed Feb 12 10:49:57 2014