Obliquebanded Leafroller from Pear Tree

2015 January 7

On June 7, 2014, we noticed that several of the leaves on one of our young pear trees were rolled into tubes held shut by silk.

As one would expect, the culprit was a little caterpillar, which we can see poking out its little black head here:

After unrolling the leaf, we found that it was a fairly uniform green, with a black “shield” just behind the head.

As we can see from this shot of it crawling on my finger, it was a bit shorter than the length of my forefinger from the fingertip to the first knuckle.

Since it was infesting a fruit tree, I figured there was a good chance that it would be listed in the book “Common Fruit Tree Pests”. And it was.

It is an Obliquebanded Leafroller, Choristoneura rosaceana. The caterpillars are a native North American species, but they eat leaves from a wide variety of both native and imported plants, including the rose family (roses, apples, pears, plums, etc.) and the heath family (blueberries, cranberries, etc.). They can get numerous enough to be significant pests on any of these plants, although it looks like they are more likely to be significant on blueberries. The big problem is that they evidently start by eating blossoms and just-forming fruit, before moving on to rolled-up leaves when they get older. In fact, there is a good chance that these caterpillars are part of the reason that we didn’t get any pears in 2014, even though both trees bloomed and there were plenty of bees to pollinate them[1].

They mature to a brown tortricid moth, with two generations per year. They overwinter as young larvae from eggs laid around August, so the first thing in the spring they are already big enough to do damage to fresh blossoms.

[1] The first pear tree was just planted three years ago, and the second two years ago. Last year, the first tree had one single pear, which was small and deformed, but delicious. This year, though, there was nothing.

4 Responses
  1. January 9, 2015

    You’re a couple of weeks late posting this, given the seasonal nature of the song in which this creature is mentioned. Hint: It’s the one with the refrain “…and an obliquebanded leafroller in a pear tree.”

  2. January 10, 2015

    You’re right, I missed my chance. Now I wish I’d thought of that at the time. Maybe there will be something else eating our pear tree that can be used next Christmas!

  3. January 21, 2015

    So is the leaf already rolled up before the critter gets there or does its rasping of the leaf cause it to roll up?

  4. January 22, 2015

    The caterpillar definitely makes the leaf roll up. It looks like it does this by hauling on silk lines that it attaches to the leaf edges, and then binding it closed.

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