Dendrobium beetle larvae

[SouthPark]

This was the first time I encountered a significant attack on my catt type orchids heheh.

It wasn't that bad fortunately. But will keep my eyes out - just in case.

The long-lasting flowers of the cymbidiums may have started to attract the well-known Dendrobium beetle - well known in Australia that is. This brought along with it the larvae - that obviously hatched.

The Dendrobium beetle left a tell-tale sign ----- lots of stringy-foam (that really looks like or IS stringy white dried foam material) ----- all over one of the cymbidiums. Apparently within that is where the larvae hatch out from.

I've never encountered them before at my place until now. Apparently these things can be devastating to dendrobiums and other orchids.

I sprayed the cym with carbaryl - hopefully it helps to protect that cym.

A tiny concern was that I found one of the larvae on one of my mini-catts ..... and it appears to have dined on a sheath ------ not only taking out and destroyed the sheath, but the new leaf associated with that same sheath too. I transferred the little larvae to one of my house-plant leaves - far enough away from the orchids. But if I do see another attack on my orchids from these things ------ I might have to bring out some counter-measures heheh.

Dendrobium beetle larva pic1
Dendrobium beetle larva pic2

[estación seca]

Does Bacillus thuringensis (BT) work against this pest?

[SouthPark]

Originally Posted by estación seca

Does Bacillus thuringensis (BT) work against this pest?

Not sure yet ES! I'll look into that. Thanks for the heads-up about BT! Always excellent to know of possible treatments to stop things from wiping out whole plants! Thanks ES!

[Diane56Victor]

After reading a couple of articles it sounds like dendrobium beetles are quite tricky to get rid of. Lots of chemical responses required!

I have no idea if the products mentioned in the newsletter or the website are still available...or even legal to use.

The Australian Orchid Nursery has an article (2018) that mentions Diazonon followed by Confidor then a Carbaryl spray over the leaves to kill the adults.
They also have a link to a PDF on the subject.

Ive read a August/Sept 2014 newsletter fron the Qld Orchid Society that has an article on the beetles.
The Queensland Orchid Society - Welcome
The writer says he uses a wide topped jar with oil and water when he sees adults. He taps the adults while holding the jar under as he says the adults tend to drop to the ground when disturbed. He also mentions pyrethrins, carbaryl and malathion. I'm not up to date on if these are still allowed, I know malathion is no longer recommended for use on animals.
For larger collections the chemical control mentions using Bugmaster, this is just a short respite, needing applications every 3 weeks.
Another product mentioned was Killyptus.

Interestingly I didnt find very much in the way of natural methods.

[SouthPark]

Diane - thanks for your post on this topic!

Interestingly, I had seen the negative impact on some Dendrobium discolor spikes in the past due to Dendrobium beetle activity, but hadn't had any beetle and/or larvae munching my catts before.

This larva was full-on latched onto a mini-catt. At first I didn't know what it was. It first appeared like a white soft blob. It was only later when I detached it - that I noticed it was a larva.

It was too late for the sheath and the leaf associated with that particular bulb. But it's ok, as the plant has several other good bulbs and leaves.

So will be watching the growing area like a hawk ----- actually I watch the area like a hawk anyway hahaha. This was like an over-night job! I agree with those words like 'highly destructive' that sources mentioned. Impressive.

I mentioned in some other thread that I know that they're just doing their thing - surviving on this planet - as we are too. But definitely have to do something if they really do destroy the whole plant if left alone!

I will check out those methods Diane (and keeping in mind about what you mentioned about legal aspects).

And also probably grab something containing Bacillus thuringensis - I think there's something at bunnings with that ingredient in it.

[Mr.Fakename]

My great grandfather used to grow fruit trees and he had tons of homemade recipes, shame he never passed that knowledge on.

I took a lot in one of his old gardening books (from 1946 apparently, dang) and they advise to use arsenic! Good luck getting your hands on that.

The "natural" methods described are:
- Tobacco water
- Pyrethrum
- Dichlorodiphenyltrichloroethane
- Rotenone

[estación seca]

Tobacco water spreads tobacco mosaic virus. Rotenone comes from an easy to grow tropical liana, Derris elliptica. Logees used to sell it in the US.

[DirtyCoconuts]

any time i have any unwanted creepy crawlers my first response is the cayenne powder and chili flakes....many things are NOT into the spicy stuff

[SouthPark]

I just found a site a moment ago (here), where one of the posts says:

All my orchids(not just dendrobiums) are outside and unprotected, either in the ground or in hanging baskets and they were all attacked by the Beetle, to the extent they were bare sticks and hadn’t flowered for several years. For the past two months, I have been spraying them every two weeks with a Carbaryl solution of 3ml to 500ml water. I give them a good drenching, especially on the stems where the new leaves connect. They are all miraculously coming back, new growth and flowers everywhere.

The eating down to the 'bare sticks' condition is definitely concerning.

DC - the cayenne powder and chilli sounds like something I could try too. I grow some bird eye chilli and carolina reaper ----- I could probably mash some up and make a chilli water spray - and test it on dendrobium spikes in the future.

At the moment, I sprayed carbaryl, which has definitely stopped the beetles from eating the buds of the dendrobium flower spikes. There has been significantly more activity than I have ever seen. Not absolutely sure about it ------ but could possibly be due to the super long lasting cym flowers that drew them here! Not sure though.

[Leafmite]

Many years ago, when we had Japanese beetles on our fruit trees and nothing else worked to kill them, Carbaryl was instant death to them. They would land on the plant and a minute later, fall from the leaves, dead. Just make certain that, when you spray, get every surface well covered. Keep pets away, wear safety gear and shower quickly after.
It lasts until the plant gets wet (contact pesticide) and then you need to spray again (so water from the bottom and spray again after it rains). Good luck!

Carbaryl - Wikipedia

---------- Post added at 11:41 PM ---------- Previous post was at 11:38 PM ----------

Originally Posted by estación seca

Tobacco water spreads tobacco mosaic virus. Rotenone comes from an easy to grow tropical liana, Derris elliptica. Logees used to sell it in the US.

I haven't seen Rotenone in a while. It was quite common once as a pesticide for fruit trees and roses. That and Lindane....