I'll jump on what Ray is asking.
My initial thought was "attracting"? How do you know those weren't loaded with eggs when you introduced those plants into the greenhouse?

I don’t know what is available for insecticide bombs these days.

I have used Whitmire microencapsulated insecticide bombs in the past. Close up the greenhouse, click them open and haul ass....

They’re fine for foliar treatments, but seemed to do little for “subterranean” pests.

I bought myself a Tyvek suit, gloves and a chemical/mist respirator, and took to hand spraying from a 5-gallon pump lever backpack sprayer.

After employing the requirements I mentioned above, the need to do that was minimal.

There's a real fine line (or actually no line) between the words pest and (I just made it up) non-pest. I know that - like pretty much everything - it's a definition. I remind myself that those 'pests' (insects etc) are just out there in the world too - like us - to survive etc. They just eat and do their own thing, just like we do. We also have to remember that humans destroy much more of the earth than do what we call 'pests'. There's the fine line (or no line).

When we use the insecticides, we may destroy not only what is attacking the orchids, but collateral damage (other insects etc too).

But ------ even though spidermites are the only things that go for some of my orchids here, and that I haven't used it before ------ I'm wondering where certain automated timed sprays can help - at night times that is ---- if it isn't too breezy or windy. The timed pyrethrin sprays. It's possible to buy cannisters in bulk (eg. pestrol brand in australia, or some other brand), and place the cannisters (with their battery operated mist ejector tops) in strategic spots, and have them fire puffs of pyrethrin mist into the air every say 1 hour or so.

Otherwise - occasional applications of azamax, imidacloprid, etc will help. As for snails ------ tactical design for the green-house may be needed.

Fortunately, I've never had snails (except hiding in pots and media of incoming orchids through the mail).

That's what we used too, Ray.

It's like the definition of "weed". If it ain't supposed to be there...

Those are never intended for use outdoors or in any unenclosed space.

Or maybe 'we don't want it to be there'. A lot of weeds are either just part of the environment -- or they were introduced or spread by ....... guess who? .... us people. While it is all natural - us people are probably the biggest pests and weeds on the planet. It's still a natural thing though. All part of nature. But I know what you mean and where you're coming from Ray.

I think you're right in general. Although, this one here does say - for outdoor usage. Whether it really is or not ------ not sure heheheh. Click Here.

The above doesn't mean I'm on the insects etc side! Just reminding us that those insects etc are just doing their thing - like we do our thing on the planet heheh. It's directed at the very topic itself 'plants that seem to attract more pests to the GH' ------ nurseries and farmers etc are constantly needing to work on protecting their plants/crop.

It's normal for those poor innocent 'souls' --- insects etc to come in at various times (not their own fault) - and there may be needs to apply treatments to prevent damage to whatever we are growing. It's normal.

In my mind ----- I'm thinking --- if we know that the insect etc is going to ultimately destroy the orchid or plant, then that's one consideration. The other consideration is about destroying something that marks or causes some superficial damage (but wouldn't destroy). Just some things I think about only. Not for imposing on somebody heheheh.

Also - flowers etc that have scents are going to attract things. Even if some plants 'might' attract more insects of some sort ------ many plants - orchids included - are normally going to attract insects etc already.

I know that spidermites can and probably will take out an entire plant - quite quickly too. So unfortunately, I do have to keep those ones under control!

The disease spreading thing is another consideration for sure. All this really highlights that 'life can be tough and unfair' thing.

I usually try to avoid harsh measures when it comes to insects (fungi and bacteria are another story). I have avid that I’ve never used for fear of contaminating my yard which is home to many native bees.

I think this week much of the problem will have subsided as I will take many plants outside where there are many more predators. I will use that time when they plants are outside this season to better prep the GH for the fall.

I think one of the things beyond pesticide usage that I am going to change is the environment of my greenhouse.

When I put my orchids into the greenhouse it was an extremely rushed job as it was October and the completion of the structure was very delayed. I never got time to put in a proper floor which is a project I am going to do this July. Right now, the floor is just earth that doesn’t drain well. I intend to make a floor of paving stones on top of sand/gravel.

The shade-cloth I use does prevent most things from getting into the vents so I am not so worried about that.

proactive predatory insects?

a couple lady bugs will eliminate the afids

I used to go around the yard looking for praying mantis egg cases, then move them into the greenhouse. It’s amazing what a zillion tiny mantises can do to a pest population!

It’s also “amazing” when you go into the greenhouse, unaware that they have hatched, and those zillion little critters jump on you. “Amazing” along the lines of walking into a large spider web in the dark.

Oh hellsno! Ain't happening... nope, nope, nope. No one left to take care of the greenhouse when I've had a heart attack. Those things give me the shivers.