How do fly-pollinated orchids attract flies?

Fly-pollinated orchids employ a variety of strategies to attract their pollinators, ranging from offering rewards to sophisticated deception.1

Attraction Methods

• Nectar and Scent: Unspecialized orchids may attract flies by producing sweet odors and providing nectar in open, shallow nectaries.1
• Deception: Many orchids attract flies by mimicking decaying substances, dung, or carrion. These flowers often emit putrescent, foul odors and feature dull colors like green, brown, purple, or red, sometimes with checkered or blotched patterns to resemble rotting flesh.1
• Visual Mimicry: Some species, such as B. nocturnum, are thought to mimic fungi in both shape and scent to attract nocturnal flies.1
• Structural Guides: To assist poorly oriented flies, these orchids often feature large landing surfaces, "tails" produced from flower parts, or fringed lips with motile, clublike hairs that vibrate in the wind to catch the insects' attention.1

Trapping Mechanisms

Fly-pollinated orchids frequently use traps to ensure effective pollination. These include:
* Saccate Lips or Joined Sepals: These form a structure into which flies fall, forcing them to crawl through a specific tunnel that passes the stigma and anther.1
* Hinged Lips: A balanced, hinged lip may tip under the weight of a fly, launching the insect into the flower's reproductive structures.1