beneficial insects!!

Can't really speak from a growing point of view but from a ecological point of view YES, the little insect houses are worth having (and high nectar producing flowers).
They are easy to make if you find them a tad expensive (which I do).

Open single flowers like calendula attract hoverflies, as well as bees of course

Sweet peas are loved by bees too, and Verbena bonariensis (those tall purple waving flower heads) are also excellent


I also plant (to be done in the autumn if as corms, not potted plants) crocusses as early insects love these

If you're interested in beneficial/pollinating insects, it might be worth checking out Sarah Raven's recent series on bbc iplayer (called something like 'Bees, Butterflies and Blooms') - some informative stuff on insect-friendly planting.
Supposedly she launched a scheme where all the garden centres were supposed to put special labels in the plants that were pollinator-friendly, but I had a look in Blooms the other day and couldn't see any. They did have a section of small wildflower plants though, most, if not all of which would be attractive to insects.
Ditto to borage, and phacelia for annuals, lavender and solidago are also very popular, but obviously more permanent.
I have never bought an insect house, but you can just tie up bundles of broken canes, sweetcorn stalks and other hollow stalks, and leave them in sheltered places.

i plant lavender along sides of path and it is swamped with bees & hoverflies all summer,also poached egg plant although that does spread itself around a bit plus tagetes and marigolds

handy cheap idea there Tony. thanks, Joyfull.

They love cosmos too