They found us. The enemy slithered beneath the 10 mil. plastic protection, or perhaps hitchhiked on a dirty trowel. The slugs and snails could have hidden craftily in the cracks of the cement or may have been dragged along the bottom of a shoe.

However they arrived, I found one slug and seven snails in our greenhouse Monday morning. I could see they had quite a party, masticating through tender tomato sprouts, toppling the stems of kale.

They seemed to have enjoyed attacking the most vulnerable — the youngest plants just recently stretching toward the light. Or maybe the moist path simply made things easier for their joy-filled ride across our six-pack plastic planting containers.

It’s one thing if the loss of dozens of defenseless plants had been my loss alone. Yet, these tomatoes were tenderly planted by my students. The children measured to a depth of a quarter or half an inch and handled a tiny seed. They cupped their hands to let water fall gently — like rain. They stayed (mostly) attentive as adults explained how roots would reach into the soil, then a sprout would appear.

A few days later I showed what reality looks like.

Just so you know, many of my children love snails. They find them in the garden and give them names. They let the mollusks crawl up their forearms and watch with wonder as their antennae feel the breeze.

This day I heard grumbles and grunts.

Of course, it’s all part of the lessons of life.

“Remember in the book ‘Farmer Boy,’ when Almonzo’s family worked so hard to save the corn crop from the freeze?” I said with the kind of tone people use when they are taking out the garbage. “Growing things isn’t always that easy.”

I shouldn’t complain. We still have 60 tomato plants that have been transferred to pint-sized milk cartons. We’ll rescue more milk cartons from the lunch garbage can and keep plugging seeds in the ground.

Our goal is to sell the plants at our school’s May Faire, and raise money for future field trips.

The garden gurus reassured me with reasonableness. We still have time for heat-tolerant spinach, followed by squash and cucumbers.

Perhaps more importantly, I now know that greenhouses need the same type of protection we provide our plants outdoors.

The University of Connecticut compiled some helpful hints about preventing snails and slugs in a greenhouse at bit.ly/UConnSlugs.

My children have only me to blame for tracking down this information after what we now call the Great Third Grade Tomato Plant Massacre.

Among the tips from the university:

• Keep a clean greenhouse. Rinse off tools and check the bottom of containers that will be stored inside.
• Water in the morning, providing less smooth surfaces for critters to slither.
• Check daily (or hourly) for slime trails. Track the trails to your offensive critter.
• Store plants on metal racks. Wood has more crevices for tiny slugs to hide.
• Create copper barriers, including copper tape sold at gardening stores. This creates something like an electric fence as the mollusks get a shock when they encounter copper.
• Remove weeds directly outside the greenhouse. Plants can become a breeding ground for invaders that will somehow think your prized sprouts are tastier than the weeds within which they were born.
• Use heinous chemicals sparingly.

In my garden at home I use Sluggo, a product that contains iron phosphate. Snails and slugs feed on the grain in the pellets, then can no longer eat and will die.