How long do insects live?    

Courses Home Knots Equipment Fly Reels Fly Lines Leaders Fly Rods Insectology Flies Fish Casting Reference library Course map   Course topics What are "insects"? Simply insects Keeping insects simple Basic insect ID Insect life cycles Comparing stages Where insects live Aquatic environment Insect adaptations Mayflies Caddisflies Dragon/Damselflies Stoneflies Terrestrials Stream order Lentic zone Lotic zone   Insects covered Alderflies Ant Blackfly Caddisflies Caterpillars Crayfish Crickets Damselflies Diving beetle Dobsonflies Dragonflies Fishflies Gnats Grasshoppers Mayflies Midges Mosquitoes Scavenger beetle Scud Shrimp Sowbug Spongillaflies Springtails Stoneflies Water bugs Water beetles Water penny Whirlagig beetle

    A "generation" is a complete life cycle of an insect, from egg to egg.  Most of the developmental time of aquatic insects is spent in/under the water (the "aquatic" stages.)  Insects that spend long periods on the land ("terrestrial" stage) usually do so in an inactive state. 

Females of many aquatic insects "oviposit" (the act of laying or depositing eggs) in the water by dropping eggs on or into the water while in flight or while sitting on the surface.  Some enter the water and dive or crawl to an underwater surface.  Others lay eggs on above-water vegetation.  Larva that come from these eggs crawl or fall into the water upon "eclosion" (hatching from the egg.)

Many aquatic insects are "dormant" during  parts of their lives when they are immobile and do not grow.  This is usually associated with adverse environmental conditions, such as seasonal changes that are common to most of the freshwater places we fly fish.  Other instances of dormancy are related to drought, intermittent water, extreme cold or warmth, or lack of food. 

    The length of time a generation takes to complete varies greatly.  The mosquito, for instance, requires a week or less to go through a generation.  Some dragonflies, conversely, may require as long as 5 to 7 years for their generations to complete.  Generally speaking, in temperate environs in North America which is our focus, with warmer, seasonal periods typical in fly fishing regions, the active terrestrial/adult stages of aquatic insects is relatively short-lived.

    Most aquatic insects leave the water in association with a major metamorphosis phase . . . such as transformation to the "subimago" (mayflies), to the "pupa" (caddisflies, beetles, etc.) or to the "adult".  In "insectology" terms, the change from the aquatic to adult winged stage taking place on the water we call "hatching"; the term "emergence" refers to the change into the adult, but is more general and not necessarily associated with surface transformations.

    Some insects emerge over an extended period of time, and larval stages may be found in different sizes.  In others, all the individuals in a given stage will emerge at nearly the same time and be the same size.  The "quicker" the life cycle, the more likelihood of finding the more "synchronized" forms.  In this kind of circumstances, the phenomenon of "swarming" (congregation of flying adults) is generally evident as a means to promote efficient mating.

    Home / How big are aquatic insects?