systemics with orchid pests

[birkie]

I have a major problem with sow bugs and slugs on my orchids that are benched. I think I have controlled the slugs by placing the pots into deep water thus forcing the pests up onto the plants, but there may be more I haven't found. My greenhouse has a gravel floor and adjoins the barn so bugs have easy access. The sow bugs are in most of my big pots and I would like to use a systemic on everything. The one I have is Hi Yield Di-syston although I understand this is no longer used for some reason. Is this safe, and how often should it be used?