Q.
I wish to know the entire life cycle of the mayfly.
I have also heard the term wiggler and would like
to know which stage of cycle this is.
A.
Because there are many variations in the life cycle
of different mayflies in terms of temperature requirements,
unique behavior, etc., I will present here a generalized
life cycle which fits most, if not all, mayflies.
We'll start with the eggs, which may be deposited
in various ways but eventually become attached to
the substrate. Embryonic development within the
egg usually takes place in a few weeks prior to
hatching into the nymph stage. However, it has
been shown that the eggs of some species (often
in temperate climates) pass through a diapause
stage; this means that the egg remains dormant
for several months before hatching. Anyway, when
the nymphs hatch, they undergo numerous molts as
they grow, called instars. As the nymphs grow and
mature, they eventually accrue the necessary number
of degree-days for them to emerge. The initial adult
stage is called a subimago, which is a winged but
sexually immature stage. This is a short stage
lasting as little as a couple of minutes or as much
as 48 hours. Finally, the subimagos molt again into
the sexually mature adults or imagos.
So briefly, the life cycle is egg to nymph to subimago
to adult; eggs may pass through a dormant diapause stage
and nymphs pass through several instars.
Don't hesitate to contact me if you want more detailed
information on mayfly life cycles. I'd be glad to give
you some references to publications that go into
considerable detail.
The second part of your question pertaining to the name
"wiggler" is a bit harder to address. If you heard this
term applied to mayflies, then the only life stage that
would even fit this description would be the nymphs.
Many move by wiggling movements in the water column or
among the rocks on the stream bottom. However, the
larval stage of mosquitoes (order Diptera) are often
referred to as "wigglers," so whoever you heard this
from may have been talking about them.
~ C. E. (Bert) Cushing, aka Streamdoctor
105 W. Cherokee Dr.
Estes Park, CO 80517
Phone: 970-577-1584
Email: streamdoctor@aol.com
The 'Stream Doctor' is a retired professional stream ecologist and
author, now living in the West and spending way too much time
fly-fishing. You are invited to submit questions relating to
anything stream related directly to him for use in this Q & A Feature
at streamdoctor@aol.com.
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