Patience with Garden Pests: Part 3 - Biological Control

Hello happy gardeners. I hope all is well in your desert garden. Today I would like to continue my four part series on organic pest control by talking about one of my favorite topics; Biological Control. Controlling pests by introducing beneficial predators or pathogens is known as Biological Control. It's good bug vs. bad bug. Now you may be asking yourself, bugs are destroying my garden and you want me to attract MORE bugs! I know it sounds crazy, but one of our best organic allies against the pest nemesis are the pest's natural insect enemies.

Before we go any further, I would like to put the use of Biological Control into perspective.  As we learned in part one of this series, the best way to keep insects from becoming pests is to create an environment that allows your garden to thrive on its own. This is known as Cultural Control. Pests don't flock to healthy plants the way they do to stressed plants. Part of creating a more healthy balanced ecosystem in your garden means providing an area near or in your garden where Beneficial Insects can feed and reproduce all year long. It needn't take up a large area to be effective, a 3'x 3' space dedicated to specific plants that attract beneficials will provide all the food and shelter they need to be happy. By providing this area we can naturally increase the amount of  beneficial insects that will visit our vegetable garden to feed on unwanted pests. The more we can do to create a healthy ecosystem before insects become pests will help us down the road if an infestation does occur. Creating a beneficial insect habitat now will also help us later on if we need to purchase beneficials as added reinforcements.

When it comes to attracting beneficial insects, one family of plants reigns supreme. The Apiaceae or Umbelliferae family is home to some very common vegetables and herbs. Carrots, parsnip, cilantro, dill and parsley are just a few of the many plants in this family. The reason beneficials love plants in this family has to do with both the fragrance they put off and the shape of their flowers.  As the name suggests, plants in this family have flowers that form in the shape of umbrellas. This curvature and mass of small flowers, called an umbel, provides the perfect feeding area for predatory wasps, hoverflies, lacewings and many other beneficial insects. We can increase the effectiveness of these plants by strategically planting them in between rows of pest susceptible crops. Interplanting in this way is a great example of Companion Planting. Rather than try and purchase individual varieties of every plant in this family I suggest purchasing a seed mix such as PVFS Good Bug Blend. This seed mix is full of plants that will re-seed themselves year after year while attracting beneficials to your garden. Easy-peasy.

Now that we know what plants we should be using to attract beneficial insects to our garden, how can we identify them once they are there? For starters, here is a list of some common beneficial insects you may use to get a basic idea of what I am talking about. As you can see the list is quite extensive. Of course you are not expected to memorize what each one of these insects look like right now, but I can almost guarantee with enough time you will become pretty familiar with a lot of them. I'd be willing to bet that you recognize one or two of them already!

Notice also that there are pictures of the different life stages of the particular insects.  It is important to know what different insects look like at different stages of their life cycle.  A praying mantis nymph for example looks like a miniature version of the adult. Ladybug larvae however look like mini orange and black alligators, nothing like the adult version we are all familiar with. It is also important to know how to identify beneficial insects in their different forms so you know at what stage they will be feeding on the pest you are dealing with.

The Green Lacewing (my personal favorite beneficial insect) is a beautiful bug that you will often see on your windows at night. It's too bad that these adult lacewings feed only on nectar and pollen. Lacewing larvae on the other hand are a voracious predator that feed on a myriad of garden pests. Ladybugs feed on pests both as adults and larvae. Providing an area in your garden where beneficials can reproduce will insure there are always plentiful and hungry beneficial insects of all ages if and when pests arrive. Take note that some beneficials are not visible to the naked eye. Trichogramma wasps, for example, are so tiny that multiple wasps fit on the head of a pin! Unless you have an extra microscope lying around...you get my drift.  Keep faith that if you build it, they will come.

Lastly, I wold like to discuss introducing purchased beneficial insects into your garden. Purchasing beneficials is a great way to control pests but it is not for the faint of heart. It isn't often that you can literally watch your money fly away, but that is exactly what will happen if precautions are not taken. For many reasons I would only suggest purchasing beneficials after cultural and physical control measures have been exhausted. As with other forms of organic pest control, there is a time and place for using Biological Control. It is important to note that although introducing beneficials to your garden can be helpful, the results are not often immediate and are most always temporary. 

One approach to introducing beneficials involves purchasing a large number of insects and releasing them with the hope that they will provide immediate pest management.  This method of pest control is called "inundative" biological control. This inundative approach often requires significant monetary investment to achieve noticeable control, but the reduced use of pesticides reduces environmental impact. Once the pest insect, or food source, is gone however so too are the beneficials you paid for to control them. The use of row covers can help to extend the amount of time beneficials stick around in your garden. Just don't be surprised if the ladybugs you released one day are no where to be found the next.

Alternately you may decide to release beneficial insects with the hope that they will establish themselves long-term. This approach, known as "innoculative" biological control, is much harder to achieve and will only work if a habitat for beneficials has already been established.  If you've purchased beneficials without the habitat, don't worry you can try and keep them around by placing some attractants around your garden.  These can be purchased, or you can make a homemade version by rubbing some honey or molasses on a 3x5 index card and hanging it from your plants.  Releasing your ladybugs at night can help to keep them from flying away immediately. Lacewing eggs can be kept in the refrigerator for weeks and released a few at a time. Just remember that no matter what you do, sometimes a bug just decides no matter how inviting your garden may be he just wants to live in your neighbors oleander.

Well thats all for today. Visit some of these great companies if you are interested in learning more or if you would like to purchase some biological control for your garden:

ORCON - California's own...
Peaceful Valley Farm Supply/Grow Organic -  A great place for all sorts of goodies!
Gardens Alive! - Hoosier state. It's Alive!
Nature's Control - Out of Oregon.
ARBICO Organics - Southern Arizona based company.

Also check out these links to learn more:

UC Davis IPM
Resource guide for Organic pest and disease management


Happy Gardening!