If you had asked me a few months ago whether I’d rather have wasps or caterpillars in my vegetable garden, I probably would have answered, “Caterpillars, obviously! They’re so cute, and they turn into butterflies.”

That answer would have inspired a fair amount of eye-rolling (and possibly even a spray of hose water in the face) from the experienced gardeners I know. Caterpillars, it turns out, are definitely not polite guests at a garden party – especially when it’s a tomato garden party. Having learned this the hard way, I can now confidently report that caterpillars such as the Tomato Horn Worm will unabashedly eat your tomatoes and then poop all over your garden.

Exhibit A: Caterpillar nibbles.

Exhibit B: Caterpillar poop:

Like I said: Not polite guests. (Can you believe the size of those caterds?)

Wasps, on the other hand, are best known for their painful and sometimes dangerous sting, so it might surprise you to learn that there is a genus of “stingless wasps” called Trichogramma. It might also surprise you to learn that Trichogramma are very good guests to invite to a garden party, because they attack over 200 species of pest insects, including – you guessed it – the tomato hornworm caterpillar!

So, how do you extend a garden party invitation to Trichogramma? Well, one way is to order them through the mail. There are a number of companies that sell Trichogramma. Mine were from Orcon, ordered through Amazon.

Don’t worry, you won’t have a box of live wasps arrive at your door.

Trichogramma are parasitic wasps: They lays their eggs inside the eggs of their host. When the Trichogramma eggs hatch into larvae inside the pest egg, they immediately feed upon the immature pests, killing them before they are able to hatch. The Trichogramma completes its development inside the pest egg and emerges as an adult. Then the cycle begins again.

Those cups each contain one card-square with a colony of approximately 4,000 moth eggs glued onto it. Inside these moth eggs, the Trichogramma are developing.

Taking care not to touch the side with the eggs glued to it, I hung two of the cards from the tomato cages, and one directly on a vine.

It’s been a few weeks since I introduced the Trichogramma, and I’m happy to report that as of late, I’m seeing more wasps and no trace of caterpillars.

Have you brought beneficial bugs into your garden?