Orchids are flowers with three sepals, three petals (one of which is modified into lip) and instead of stamens and stigmas in a more typical flower, they have a column which is a combination of both. The lips and coloums can be very ornate and are often the visual cues we use to identify them.
Many orchids have complex and specialised reproduction process. Generally speaking flowers offer rewards to their pollinators in the form of nectar or edible pollen. Orchids have evolved a few different strategies to achieve pollination.
Some do it by means of sexual deception. Many have only one pollinator and the insect visiting does so because he mistakes that particular species over and over for his mate and in the process of trying mate with it he gets the pollen attached to himself which is then transported to the next flower he visits. This can happen because in some of these insect species the males mature slightly before the females so the flowers are the closest thing they will see to a female for a little while. It also demonstrates that timing in nature is very important. If the wasps for some reason matured before or after these orchid flowers then nothing would pollinate them.
Although we know about the pollinators of many flowers there is still a great deal we have yet to find out. One of the really common orchids- the Waxlip, we still don't know what pollinates it.
The spider orchids are often associated with wasps trying to mate with them.
Some orchids like some of the sun orchids can self pollinate. There are also those that mimic other flowers that do produce nectar, and so get visited by its pollinator in the expectation that there will be a reward (the nectar). The donkey orchids are very similar to the many pea flowers in the area and so are visited because of a visual similarity. Odour from nectar bearing flowers attracts them to the area but when they get close it is visual.
If we somehow could remove insects from the picture many of these flowers would disappear to. There are many complex relationships between organisms that we have still yet to work out but we should look at each species like a piece of a jigsaw puzzle. Imagine we started with the complete picture and as we encroach on these areas that we don't understand properly we are removing pieces, each time another species disappears the picture is a little less clear. If we loose too many species the picture wont be coherent at all. With the many endangered species here, quite a few in the orchid family, it is time we started thinking more about how we look after what we still have.
0. Flying Duck orchid
1. Hyacinth orchid
2. Hyacinth orchid
15. Sun orchid