Parasites on trees

[ruweiss]

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.

[Lesley Cox]

What odd - and horrible - things. I've never seen anything like them.

[ranunculus]

We have seen similar instances in America and northern England quite recently.

[gote]

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

[cohan]

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..

[Kees Green]

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.

[cohan]

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

[Anthony Darby]

I must admit I had a double take when I saw "parasites on trees" and was expecting something on mistletoe plants.

[ArnoldT]

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.

[Kees Green]

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

[fermi de Sousa]

All I can say is lucky we do have cane toads

Kees,
I presume you meant to say you DON'T have cane toads
Would you like some?
cheers
fermi

[Lesley Cox]

All I can say is lucky we do have cane toads

Kees,
I presume you meant to say you DON'T have cane toads
Would you like some?
cheers
fermi

Yes he did and no we wouldn't.

[Paul T]

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.  

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.

[Stephenb]

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

[Lesley Cox]

Trade you Paul. One cane toad (male) for 20,000 possums. We can be generous too.