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Deadly Enemy of Japanese Beetles: the Tachinid Fly

April 8th, 2009 by Veggie Master · 5 Comments

One of the unsung predatory heroes of the garden which works diligently to keep the bad bug population down is the Tachinid fly.  Out of more than 8,200 known species, nearly 1,300 reside in North America today.  

Most Tachinid flies are parasitoids, meaning the larvae develop inside a living host, ultimately killing it.   A few are parasitic in that they live off the host but do not kill it. Caterpillars of butterflies and moths, adult and larval beetles, sawfly larvae,  and various types of true bugs and grasshoppers are parasitized by Tachinid flies.

Istocheta aldrichi  is one of the few species of the fly that is host-specific.  In 1922 this insect was imported from Japan to combat Japanese beetles in America.  The fly parasitizes the adult by glueing its eggs to the thorax of the beetle.  The larva hatches within 24 hours and bores into the beetle to feed.  Hooray, help against the predacious Japanese beetle!

Tachinid fly eggs on Japanese beetles

An organic approach to pest control in your garden is mandatory, or you will be destroying this wonderful army of beneficial insects along with many others.  Caring correctly for the garden environment will pay off in many ways, including a big improvement in the flavor and extended storage life of your fruits and veggies.

The next time you’re in the garden and see a caterpillar or beetle with tiny white eggs attached to its back, leave it alone.  The pest is done chowing on your plants and its demise is quite imminent.

When it comes to Japanese beetles, I hand pick them in the evenings and drop them into a container of soapy water.  I leave any beetles that have already been parasitized because I want to increase my beneficial insect population and make my life a little easier.  Tachinid flies can have up to two generations per season in the northern United States (more in the south).  One female can lay 100 eggs each time, so the numbers add up fast.

After all this exciting news I bet you’re wondering why they don’t make a bigger deal in the press about Tachinid flies.  Well, they are not the most handsome of insects.  Most Tachinids closely resemble the common house fly except that they are rather bristly and tend to be dull in color.  A few species in the family are a bit more flamboyant and can be colored bright red to orange.

Photos curtsy of Wikipedia

The adult Tachinid fly feeds on nectar, pollen and honeydew secreted by certain insect pests.  If you wish to have your own army of these good guys in your yard, invite them to hang out by planting sweet clover, dill, buckwheat, parsley and other herbs and flowers in and around your garden.

Happy Gardening!

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