Tuesday, June 05, 2012

Annabelle Hydrangea - Leaftier Moth


Each year, I've noticed greater populations of the Hydrangea Leaftier (Olethreutes ferriferana). Today, I counted nearly all of the tips of the Annabelle Hydrangeas in our planting bed having these worms cocooning themselves between the terminal sets of leaves.

When you find these pockets made from leaves mixed in with the lovely snow-ball flowers, you can help but be curious.



They won't kill off the plant. It just stunts the plant from flowering. What is a Hydrangea without its Mop-head blooms?



Soon after the Leaftier worm hatches from its egg, it travels to the terminal shoots of the hydrangea. It excretes a silken thread that binds the two unfurling leaves together. Making a dandy shelter for it to feast and pupate.
When you open these "pockets", inside you'll see a black headed green worm and its castings (frass pellets). It eats the flower and any newer leaves developing inside until it pupates. Quite ingenious method of survival.


Generally, one wouldn't even notice these leafy pockets, until the contents inside have been thoroughly eaten. The pocket begins to become brown and at this point, the worm has begun its pupating journey to become an adult moth.


No topical pesticide is useful, since they make these elaborate shelters. The way to get rid of them is to pinch off these pockets and or open them up and squish the worm inside. Many times, the worm has just sealed off the leaves and has not eaten the flower within. BTK (Bacillus thuringiensis var. kurstaki) is also useful to spray as a preventative, when new growth emerges in mid-may.

I've sprayed newly emerging foliage with water to dislodge any young worms from getting to the terminal shoots in early-May, to mid-June. Although, it's quite an arduous task and it may damage new leaves. Just keep your eye on the tips of the new growth. Generally when Bridal Wreath Spirea (Spiraea x vanhouttei) is in full bloom, is when young worms begin to bind the terminal leaves together.


Here is a picture of an adult moth: 

Photo: Mississippi State University_ Moth Photographers Group

Ridding the plant of as many cocooned nests as you can, will eventually rid you of the moth ever returning to lay more eggs. You may lose some flowers this year, but next there will be less moths.


4 comments:

  1. Heidi! Thank you! My Annabelle's are 6 yr.s old and have always been healthy producers of big flowers until I discovered this problem for the first time this yr. in zone 4b (just 2 hrs. N. Of Toronto on Georgian Bay)...I snapped off over 2 doz. closed bud tips today! It's June first and we've had so little rain this yr. that the shrubs are a bit behind where they usually are growth wise...do u think there will be time for lateral branches and new tips to grow for flowers this year after cutting off 80% of the tips and last two leaves? Many thnx for any advice...

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  2. Hi there, 80% removal is quite a bit. The only suggestion I have is to scratch the soil beneath the hydrangea, to dislodge any nesting moth eggs; add more compost and watering the hydrangea so that it can have the means to reestablish new growth, since so much of the terminal growth has been removed. Using a good fertilizer with high middle numbers will help the process too.

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  3. I entered my 6 year old Annabelle's gorgeous bloom at our local Horticultural Society last year and it won first price as well as best overall price. Other than the fact that the blooms are so big that they fall over and with the wait of rain water they struggle to come back up, I think they're perfect and just love them.
    This spring however, I was shocked to find this ugly worms inside a "cocoon". Not knowing what else to do I cut off all infected "Pods', placed them in a pail and sprayed them with a Natural Insecticide. I also sprayed the bushes, (all 7 of them)as well as the ground. We'll see what happens.

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  4. I know. These moths seem to have weird cycles. Some years, you see only a handful. Sometimes they are on each terminal shoot. Be persistent and keep monitoring. Hope all goes well!

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