Appetite for Destruction

Okay, right off the bat, let’s get this out of the way: this is not a blog post paying tribute to Guns N’ Roses. This is a blog post that was sparked by the destruction of the roses. It all started yesterday, when I intended to weed the Poetry Garden, until something stood out like a sore thumb – the climbing roses looked bare!

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It’s not unusual for ‘Dublin Bay’ to have issues with black spot, a fungal problem that many roses endure which can result in them losing their leaves, but certainly not this early in the season and never this bad! So I took a step closer. The leaves had been munched! Immediately my mind turned to deer.

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After briefly cursing them, I realized it seemed even too early for deer. So I took yet another step closer. Lo and behold, my true nemeses revealed themselves: forest tent caterpillars (Malacosoma disstria).

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I had heard over the last week or so from both guests and coworkers that the caterpillars had been really bad this year. I didn’t think much of it, but also thought their numbers appeared higher than usual. It was only after I watched my roses being eaten before my very eyes that I too finally agreed: yeah, it certainly is a bad year for these caterpillars.

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I’m generally not one to jump the gun and accuse any insect occupying a plant of being a flora-hungry fiend. The lubbers (or those great, big grasshoppers you see here during the summer) tend to get a bad rap for just that. I usually see them lounging around on a lot of plants, but I rarely see them eating much. Giving the tent caterpillars the same benefit of the doubt, I monitored their activity. Sadly, they were just as bad as they seemed.

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These caterpillars eat the leaves of some woody plants. While they do not necessarily tend to favor roses, apparently this year, and with the large quantity of caterpillars, they opted to give them a go. Fortunately, they have showed little interest in the flowers, and the leaves will flush back out, but it may take a few weeks. With all of that eating, they left another indicator to make sure I knew they were the culprits: droppings.

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Since I am not a fan of using pesticides, and pesticide control over forest tent caterpillars appears fairly limited and can cause harm to the caterpillars we want to see and promote, my approach to managing these guys was simple, if not a little unnerving to some. I was going to remove them by (gloved) hand. I pulled them off stems, leaves, bricks, the fence, the ground – pretty much everywhere! I placed them in a small bucket so I would not lose them and could deal with them later. If you are going to remove a pest from your plants, it is best to take them off site, and not just toss them on the ground, otherwise they will simply crawl right back to where the eatin’s good!

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After about an hour or so of plucking caterpillars, I was left with an impressive, if not somewhat depressing haul. The bulk of these caterpillars were removed from my five largest climbing roses. The other roses in the same area had a small portion on them too, but had not been nearly as badly damaged as the larger ones. So what does a caterpillar collection during a bad year of forest tent caterpillars look like?

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In case this doesn’t give a good idea of just how many that is, here is what it looks like to hold the majority (not all!) of them in my hands.

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Once I had done a thorough removal of the forest tent caterpillars on the climbers, I checked the shrub roses. Fortunately, there were very few on them and the roses appeared in good health. However, I was left with one more problem – what was I going to do with all of these caterpillars? After conferring with Gina Davis, one of our horticulturists, I followed her method and brought them to a new home in one of our natural areas. They could enjoy the plant life there, without creating an eyesore and damage in the gardens. Or worse, making another meal out of my roses!