Tuesday, June 05, 2012

Annabelle Hydrangea - Leaftier Moth

I'm a huge fan of Annabelle Hydrangeas. They perform with little effort and bring so much spark to a dark corner.

However, each year I've noticed greater populations of the Hydrangea Leaftier (Olethreutes ferriferana) fusing terminal leaves together. 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 strange leafy pockets mixed in with the lovely snow-ball flowers, you can help but be curious.


Some leaves are just fused together like the ones above. At this stage, only a smaller caterpillar is inside.


Sometimes, they are so small - you only notice their poop. But look closely.


Tiny little worms/caterpillars with black heads.

The good thing: they won't kill off the plant. It can stunt the plant from flowering. What is a Hydrangea without its Mop-head blooms?



Soon after the Leaftier worm hatches from its egg in early May, 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. As the plant grows, the fused leaves become even more distorted as the caterpillar ages (shown above and below).


Depending on when you open these "pockets", inside you should see a black headed 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, unless you notice less blooms from the year before. Sometimes 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 a 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. Times can vary though, depending on the weather.


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.





22 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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  5. I loved your detail pictures of the leaftier pods. I found a ton on my hydrangeas this spring. Yet, it seems the pods have already been vacated. I only found the pods after asking a landscaper why my hydrangeas were dying off? One plant started diminishing last spring, then another one next to it started dying and this year it has spread to the 3 healthy annabelles on the other side of the steps. Since you mention that the worms only destroy the bloom, what else could be ailing my once beautiful annabelles?

    ReplyDelete
    Replies
    1. Hard to say if I can't see the plant. In some of the fused leaf pockets I found a spider eating the caterpillar - which could be your case too. They come and feed and go!

      Annabelle Hydrangeas suffer from drought and or too moist of conditions. Also from poor pruning practices. Are there any signs of green growth coming from the base of the plant at all?

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  6. would spraying the cacoons with rubbing alchol help eliminate these pests?

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    Replies
    1. No. Alcohol will only be effective if it comes in direct contact of the larvae. The larvae are tucked inside folded cocooned leaves. Alcohol in contact with leaves will just dry out the foliage - damaging the leaves. Trust me - squishing is best. It's time consuming, but the endeavour pays off.

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  7. You also have to clean up the soil, removing the mulch and the top layer of soil in the fall. The larva drop to the ground in the late summer and burrows into the soil to emerge as moths the following spring. I remove the mulch and top soil in the fall, put down new top soil, apply Bayer systemic insecticide, then add a thick layer of mulch. I only saw a few this year as opposed to last year where all my plants were covered. When you have dozens of hydrangeas in a garden, as I do, or even a few plants, the open and squash method is way too time consuming. Besides the fact that the larva moves down the shoot where you might miss some. I still say open and squash when you visibly see them but clean-up is more important in the long run.

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  8. Being thorough is key, however, with simply removing the leafier pockets, I've managed not to have any this year. I enjoyed the satisfaction of finding each one and giving them a squeeze. Each year there were less and less. I use a lot of compost and shredded leaves to help keep the soils moisture locked in and removing that would of been more time consuming than going out every other day to find the bounded leafy pockets. Glad your method has success too. Being on top of it each spring I think is the most crucial. Thanks for commenting...

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  9. We have 7 Annabelle and 2 Limelight Hydrangeas. I opened over 100 leaf pockets on the Annabelles, but had only 1 on a Limelight. Once all the Victoria Day rain stops, would insecticidal soap help kill the caterpillars. My eyes are not good enough to see the little critters, so I didn't squish any. I had some last year, but by opening the pouches had loads of bloom.

    ReplyDelete
    Replies
    1. You can try, but you'd have to have direct contact on the caterpillars for it to work. Squishing is best. It's time consuming, but once you remove the majority, less infestations will occur next year.

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  10. Thank you for this info! We moved into our home in October, so this is our first spring to see what kind of plants we have. This morning, I found almost two dozen of these closed leaf pockets. I had no idea what they were and decided to pick off the entire pocket. I could tell they weren't doing well in the first place, so I didn't want to take any chances. I guess I may have stunted growth now if I picked off these leaves? Did I pick off what would have been blooms? Is it only hydrangea plants I need to look through?

    ReplyDelete
    Replies
    1. No - not much stunted growth. Just some bald spots. Keep removing them. If the moth lays more eggs this summer, you'll have less blooms, regardless. Catch 22. Only Hydrangeas get them, to my knowledge.

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  11. Thanks for all this info Heidi! When I open the pocket sealed together, is it just 1 worm I need to find and squish?

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  12. My Annabelle was loaded with these last year but I was too late to do anything. So discouraged and not knowing what I was dealing with, I cut back the whole bush a third. To my surprise I have great growth this year but again with Leaftiers.
    I set about opening the pods and squishing the little buggers. It has become a daily inspection, almost meditative and I now have tons of blossoms!
    Thanks for the great info!

    ReplyDelete
    Replies
    1. Adults lay eggs in the soil/debris/mulch at the base of the plant too. The best results I've had is pinching each pocket.

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  13. There is a separate celery leaftier moth and probably some other plants too. Opening them carefully and getting rid of the caterpillar does seem to help but you have to start early and repeat often (it's sort of peaceful in these interesting times). My infestation is much worse this year than last year which was limited to a few plants on one side of the house-- and of course last year was the most abundantly gorgeous flowering year EVER.
    One recommendation I read was to not cut the old stalks back until late winter/early spring so that you maximize the odds of capturing the eggs and caterpillars and to NOT put the cuttings in the compost pile but bag them and get rid of them. I may try that this coming winter.

    ReplyDelete
    Replies
    1. I tried cutting back the entire plant and yet they returned. Annabelle Hydrangeas are popular. Your neighbourhood may have them. Moths need to find hosts to lay their eggs. I just keep a vigilant watch and keep finding the pouches. Keep at it. Good luck.

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  14. Many thanks for this blog. I had no idea what was going on and now I know. Education is key, so thanks for the information. Tomorrow I will squish caterpillars. Today I was battling azalea leaf scale and cottony camellia scale with Neem Oil. The fun never ends!

    ReplyDelete
    Replies
    1. Keep squishing. I squished 5 on mine this season. Not many returning anymore. It's the year of the bug - many life cycles will continue. Keep an eye on the hydrangeas to see if more than one generation takes flight. Good luck!

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