1. Ephemeroptera: Mayflies

2. In North America
17 families
680 species (569 in US)
PA species

3. Hemimetabolous
Egg
Larva/nymph/naiad
Adult

4. Larvae

5. More Larvae

6. Life History
Usually one generation/yr, some have two; others may take 2 years/generation (tend to be larger species)
Eggs always laid in water; hatch in 1 week to several months; diapause may last up to 11 months
Larval stage lasts 3-6 mos (range 10 days-2 yrs); molt many times (more than any other aquatic insect: times; 45x in some species); may vary even within species
Emergence:
Float to surface, use exuvium as raft; better be quick!
Crawl to edge (~5cm) to emerge

7. Life History continued
Have unique subimago life stage: the only flying insect that is not fully developed, i.e., sexually mature
Wings are dull and semitransparent due to fine hairs
Subimagos of same species and habitat usually synchronize emergence…why?
Subimago lasts ~ 24 hrs (range: minutes to 2 days)
Adult is imago-has shiny wings

8. Subimago (aka dun)

9. Adult or Imago (aka spinner)

10. Reproduction
Adult lives 24 hrs (range: 90 minutes to 2 days); don’t feed-have no mouth parts and degenerate digestive systems
Males-only swarm over water; have distinctive swarming behavior
Lay eggs and die; some explode!

11. Significance & Ecological Role
Mass emergences may be annoying (Put-in-Bay snowplows; Port Clinton brownout)
Most are sensitive to pollution, hence are clean water indicators
Feed mostly on algae, plant material, detritus
Are the mice and rabbits of the aquatic ecosystem: convert much of the plant matter into animal flesh
An essential link in the food chain

12. Adults

13. Trout must be really dumb