Caterpillars in My Container Garden

Every morning I check my garden to make sure things are moving along swimmingly and that squirrels haven’t been snacking on my tomatoes.

In one of my mesclun mix pots I noticed a portion of the growth was stunted. My initial thought was it was getting too much sun, but further investigation told me sun wasn’t the problem. My problem was an infestation of green caterpillars.

Over Reaction

My first reaction wash, “How dare they!” So, I ran and got my homemade insect spray and sprayed the caterpillars. The insect spray killed the caterpillars, but it also damaged my mesclun. By the next day my mesclun was burnt to a crisp.

I realized my insect repellent/killer mixture was too strong for plants, but worked extremely well on insects and caterpillars.

Infestation Spread

Next, I noticed my broccoli, cabbage and collards were showing signs of infestation. There were leaves that were totally eaten off by the caterpillars.

Chewed cabbage and a few chewed collard leaves

I tried mixing a milder soapy water solution, but decided to try something different. I searched online for a natural deterrent/killer for the caterpillars and found a naturally occurring substance called Bacillus thuringiensis .

Chewed broccoli leaves

Bacillus thuringiensis naturally occurs in the soil and is harmless to all but the caterpillars and a few other unwanted pests. This microorganism, once ingested by a caterpillar, destroys their digestive system, thus killing them. It’s not a repellent so in order for it to work the caterpillar must eat some of the vegetation. Additionally, the bacillus thuringiensis must be reapplied every week to 10 days until all of the caterpillar eggs hatch, nibble on the harvest and die (it also has to be reapplied if it rains).

The best way to take care of a caterpillar infestation is to prevent it from occurring in the first place (lesson learned).

Finding Bacillus Thuringiensis

I drove over to my local Home Depot where they had chemicalized versions of BT. In other words, their caterpillar killers had a lot of chemicals that I didn’t want on my vegetables. I left Home Depot and drove around to 3 other stores and finally found what I wanted in my local True Value store. I bought two canisters of Dipel.

To apply I mixed 1 tablespoon of the powder to 1 gallon of water in my sprayer and sprayed the vegetables. Since it doesn’t kill on contact, I spent a lot of time checking the vegetables and picking off caterpillars before they did too much damage.

Hopefully they won’t do too much damage to the collards

I realize they’ll have to eat a bit of my veggies before my infestation is totally eradicated (bummer). In the meanwhile, I’m planting another batch of mesclun mix to make up for the caterpillar casualty.

Where Did the Caterpillars Come From?

It is my belief the eggs were in the dirt. The plants that had the infestation were all planted using dirt from the same bag. In the future, no matter where the dirt comes from, I’m spraying bacillus thuringiensis to prevent caterpillar infestation.

These are the lessons I need to learn before I begin planting in the yard next year. One lesson down and oh so many more to go.

Update: I had the solution to in my gardening arsenal all the time.  After purchasing the BT, I found that diatomaceous earth also works on these little green caterpillars.