Scottish Rock Garden Club Forum
General Subjects => General Forum => Topic started by: ruweiss on June 17, 2010, 10:13:15 PM
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In our region more and more trees suffer from parasitic moths, the poor plants look
quite apocalyptic to me. I took the pictures about 2 weeks ago and noted yesterday,
that new growth starts again. The caterpillars do no harm to humans, but the species
which parasite the oak trees are really dangerous, causing inflammations and severe
allergic reactions.
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What odd - and horrible - things. I've never seen anything like them. ???
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We have seen similar instances in America and northern England quite recently.
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Some years ago we had a similar outbreak on Populus tremula which is very common in Sweden. There was no permanent damage. Unfortunately I did not take any pictures.
Göte
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that looks pretty intense :(
here also we have had in the past what we call 'tent caterpillers' on populus; it happens occasionally, and can weaken individual trees-especially if in combination with any weather stresses, though not usually....it needs to be a dry summer for the infestation to become severe, since typically in midsummer we will have some heavy rains which are not ideal for the caterpillers..there may be other factors in the life cycle of the insects that dictates when they will peak--usually you see few or none of those caterpillers, other years just a little 'tent' here and there..
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Well as I am an amateur entomologist I find it fascinating and would love to see it in person.
Nature is amazing and it is not surprising that the trees are not harmed, it would not make sense for the caterpillars to kill off their host plants.
Its a bit like the 13 and 17 year cicadas in North America, these emerge by their thousands, well more like millions, the females lay there eggs in the ends of branches and most trees loose lots of foliage, however it only acts like a natural prunning and the trees bounce back, plus the millions of decaying cicadas on the ground also provide excellent fertiliser for the next years growth. These cicadas are known as Magicicada species and there are 6 species presently.
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although, the insects may not consider it a problem to kill off some hosts when there are 'always' more trees of the same species available! and that's assuming there is a proper environmental balance..pine beetles are wreaking havoc in western canadian forests just now--they don't seem too concerned about wiping out their hosts ;)
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I must admit I had a double take when I saw "parasites on trees" and was expecting something on mistletoe plants.
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We have periodic outbreaks here in the North East US. They are either Tent Caterpillars or Gypsy Moths. Usually a single year infestation will not kill the tree but repeated yearly infestation can.
They are controlled with BT which is a bacterial agent or an insecticide.
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I should have said that native insects usually do not kill off the host plants, however this can not be held true for exotic insects.
NZ has had a few scares, one with Gypsy moths-however aerial spraying seems to have worked thank goodness.
All I can say is lucky we do have cane toads :P
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All I can say is lucky we do have cane toads :P
Kees,
I presume you meant to say you DON'T have cane toads ;D
Would you like some? ;D ;D
cheers
fermi
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All I can say is lucky we do have cane toads :P
Kees,
I presume you meant to say you DON'T have cane toads ;D
Would you like some? ;D ;D
cheers
fermi
Yes he did and no we wouldn't. :o
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Lesley,
But we'd be happy to provide some, but only on the proviso that you take all of them from Aus. We want to be generous after all. ;D
Here in Aus we get webbing caterpillars on the Tea Trees (Leptospermum) that produce the most awful webbing filled with caterpillar frass (that's manure, in non-insect terms ;)) which can sometimes kill the host plant. At the very least the poor plant is stripped of leaves.
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Here it's the caterpillar of the Yponomeuta evonymella (Bird Cherry Ermine moth) which is the nearest we come to the North American tent moth caterpillars. It's amazing that the Bird Cherry (Prunus padus) can withstand complete defoliation several years in a row. This is the first year for some years that I haven't seen it - however, it could just be the late spring. I posted a couple of pictures earlier here: http://www.srgc.org.uk/smf/index.php?topic=3720.msg102969#msg102969 (http://www.srgc.org.uk/smf/index.php?topic=3720.msg102969#msg102969)
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Trade you Paul. One cane toad (male) for 20,000 possums. We can be generous too. ;D
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Not quite a tree but when I first saw these red growths on a cactus in Chile-Echinopsis chilensis I thought it was the flowers. They are in fact the flowers of a type of mistletoe -Tristerix aphylla which is specific to these plants and is spread by one species of mocking bird
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What a wonderful sight Tony, and a wonderful story too. Red flowers on a cactus, but not its OWN red flowers, and the plant put there by a bird! I hope the mocking bird came back later to appreciate his handy work. Does the mistletoe just sit there as an attractive guest or does it actually harm the cactus host?
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Trade you Paul. One cane toad (male) for 20,000 possums. We can be generous too. ;D
;D ;D
I would imagine that the mistletoe on the Cactus would be feeding from the cactus itself, rather than just using it for support? Quite striking though, aren't they?
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I would imagine that the mistletoe on the Cactus would be feeding from the cactus itself, rather than just using it for support? Quite striking though, aren't they?
Quite right Paul - a parasite, unlike caterpillars.
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Fantastic picture, never heard of that one before. I was lucky enough to see the New Zealand Red Misteltoe in South Island, thinking it was the tree (the forest was red with flowering Metrosideros spp)
http://upload.wikimedia.org/wikipedia/en/d/d7/DSCN5417-red-mistletoe_rebal_b.jpg (http://upload.wikimedia.org/wikipedia/en/d/d7/DSCN5417-red-mistletoe_rebal_b.jpg)
I think I also remember that the misteltoe was under threat from those possums....
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Wow, what a picture Stephen. :o
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Not mine, unfortunately, but yes...
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What a wonderful sight Tony, and a wonderful story too. Red flowers on a cactus, but not its OWN red flowers, and the plant put there by a bird! I hope the mocking bird came back later to appreciate his handy work. Does the mistletoe just sit there as an attractive guest or does it actually harm the cactus host?
Stephen a wonderful picture.
Lesley research has shown that the mistletoe has a significant harmful effect on the cactus. It does not photosynthesise and is totally dependent on its host.It greatly reduces its flowering and therefore fruiting capability
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That's a shame that the cactus is harmed. It seems illogical to me that a parasite will often kill the host on which it depends. So it is too, with fishing fleets which deplete the stocks so much that they are all but extinct. Then what? Won't go into the question of whaling. This isn't a polital Forum, but.....
In a good year, the South Island Metrosideros forests are rich crimson with their flowers and the mistletoe adds but is in tiny quantities, compared with the flowers of the Rata.
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Fantastic picture, never heard of that one before. I was lucky enough to see the New Zealand Red Misteltoe in South Island, thinking it was the tree (the forest was red with flowering Metrosideros spp)
I think I also remember that the misteltoe was under threat from those possums....
The mistletoes are under severe threat from possums so much so that our Department of Conservation nails metal sleeves around trees to protect them. Here are some pictures: the host is Nothofagus
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Good news from the poor trees:
The infested trees now begin to recover and start with new leaves.
At the ground around them are many of the moths, only the trunks seem
to wear white stockings.