So caught in the act

[ArronOB]

For the last few years every Oncidium spike in our shadehouse has been monstered by something. Sometimes the cattleyas cop it as well. It eats just the actual flower bud, ignoring the spike and the sheaths around the bud. Often it’s just a few buds so I still get a nice looking spike, just not as good as it should be. I went out this morning and finally caught the culprit. See the photo.

There is another pattern of damage that is just as common and even more damaging though. I’m pretty sure it’s not snail behaviour. The pattern is always the same, something chews out a little chunk of the stem of a spike 3-6mm long and almost through the stem but never quite. It’s like it tries just enough of the stem to decide it doesn’t like the taste, but enough to kill it. It’s weird behaviour because the culprit must spend a few minutes chewing which it wouldn’t do if palatability was the issue, but there is never two chewed spots, always just one. Why would something do that? It’s almost like it just hates orchids, or me.

I caught a grasshopper on a flower stem once. It was looking extremely guilty but wasn’t exactly in the act and I haven’t seen one since so the question of what is doing it is still open. Anyone seen this pattern of damage?

So what do other people do to keep macro-pests off their plants?.

The more mobile bugs can pretty much come and go from the shadehouse as they please and there isn’t much I can do about that. Nonetheless I don’t very often see bugs in there with the exception of millipedes and some type of cockroach. The snails I know I can kill with snail bait the problem is I’ve heard the dying snail will then be eaten by the blue-tongue lizards with tragic consequences. I would rather avoid using pesticides regularly. What do people like Roberta with large undercover collections do?

[Roberta]

I have also had the "half eaten" stem issue... and not caught the culprit. Suspect a caterpillar. (Possibly spraying with bacillus thuringiensis could help, or spinosad is also toxic to larvae) I don't have a lot of pest problems... since most of my collection is the back yard, there are other plants to eat so the odds improve a bit for the orchids. I think slugs are the most insidious. I had a plant in the GH, and just the one plant looked seriously nibbled. I submerged the pot in water, and a slug came out (probably gasping for breath). I used a very non-toxic remedy... squish underfoot. Very satisfying. I don't have the blue-tongued lizards, I do use snail/slug bait (the iron phosphate type, rather than metaldehyde... seems to work on slugs.) The slug bait does end up forming a gummy blob on the surface of the pot in the presence of water, I just scoop it out when it gets gross.

[minicoerulea]

Regular Sluggo (the iron phosphate product) is used routinely in reptile and amphibian vivariums without reported ill effects on non-target animals.

I couldn't find any published data for lizards, but the LD50 for FePO4 in rats is 5g/kg. Given the percentage of active ingredient in the product (1%) means that rat would have to consume half their body weight in Sluggo to reach the LD50.

[ArronOB]

Originally Posted by minicoerulea

Regular Sluggo (the iron phosphate product) is used routinely in reptile and amphibian vivariums without reported ill effects on non-target animals.

I couldn't find any published data for lizards, but the LD50 for FePO4 in rats is 5g/kg. Given the percentage of active ingredient in the product (1%) means that rat would have to consume half their body weight in Sluggo to reach the LD50.

Thanks for that. It makes me feel much better. I’ll get some.

[estación seca]

Since the opossum population exploded in Mission Viejo, not far from Roberta, there haven't been any of the introduced garden snails seen.