Ephemeroptera: Mayflies
In North America
•17 families
•680 species (569 in US)
•PA species
Hemimetabolous
Egg
Larva/nymph/naiad
Adult
Larvae
http://www.cals.ncsu.edu/course/ent425/compendium/mayfly.html
More Larvae
Life History
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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: 12-27
times; 45x in some species); may vary even within
species
Emergence:
1.
2.
Float to surface, use exuvium as raft; better be quick!
Crawl to edge (~5cm) to emerge
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
Subimago (aka dun)
Adult or Imago (aka spinner)
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!
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
Adults
Trout must be really dumb