Fishfly vs Mayfly: Unveiling Key Differences in Aquatic Insects

Fishflies and mayflies may appear similar to the untrained eye, but in reality, these are two distinct types of insects belonging to different families. While both are aquatic insects and play essential roles in the ecosystem, understanding their differences can help us appreciate the diversity of the insect world and their contributions to the environment.

Fishflies belong to the family Corydalidae, which consists mainly of dobsonflies. These insects dwell in various aquatic habitats, ranging from streams and rivers to still ponds and even tree holes, depending on the species (source). On the other hand, mayflies are part of the order Ephemeroptera and are unique among insects due to their distinct subimago stage in their life cycles (source).

This article will discuss the key differences between fishflies and mayflies, including their morphology, behavior, and their roles in ecosystems. By recognizing these differences, we can better understand the unique characteristics of each insect and the important functions they serve within their habitats.

Fishfly and Mayfly Overview

Taxonomy and Scientific Names

Fishflies and mayflies are two distinct groups of insects. Mayflies belong to the order Ephemeroptera while fishflies belong to the family Corydalidae.

Distribution and Habitat

• Mayflies are found across:
  • North America
  • Central America
  • South America
  • Eurasia
  • Africa
  • South Africa
  • Madagascar
  • Oceania
  • Australia
  • Asia
• Fishflies are distributed in:
  • North America
  • Central America
  • South America
  • Asia

Appearance and Morphology

Mayflies and fishflies differ significantly in their appearance and morphology.

Mayfly:

• Slender body
• Two pairs of triangular wings
• Short antenna
• Two or three threadlike tails

Fishfly:

• Round wings
• Feathery antennas
• Fragile

In conclusion, fishflies and mayflies are two different insect groups, belonging to different scientific families. They are found in various parts of the world and have different appearances, with mayflies having a slender body, triangular wings, and short antennas, while fishflies have round wings and feathery antennas.

Life Cycle and Behavior

Larval Stage and Naiads

Mayflies and fishflies both have aquatic larvae stages. Mayfly larvae, also known as naiads, live in various aquatic habitats, feeding on algae and organic matter. Fishfly larvae are similar in appearance but have key differences, like mouthparts.

Some features of mayfly naiads include:

• Gills for breathing underwater
• Buggy-looking eyes
• Ranging from one centimeter to several centimeters in length

Adult Stage and Mating

The adult stage for both insects is short-lived. Adult mayflies have a unique sub-adult stage called the subimago before developing into their winged adult form, also known as the imago stage. Adult mayflies have slender bodies, large compound eyes, and four membranous wings held upright together source.

During the adult stage, mayflies focus on mating, with male mayflies using their large compound eyes to locate females. Adult fishflies, on the other hand, do not have a subimago stage and go straight from larvae to winged adults.

A comparison of mayflies and fishflies in the adult stage:

Swarming and Blooms

Swarming behavior can be observed in both mayflies and fishflies. Swarms are large populations of flying insects that gather in one area for mating purposes. Both insects exhibit swarming behavior due to their short adult lifespan of just a few days.

Water quality plays a significant role in mayfly blooms, as better water quality supports larger mayfly populations. When large numbers of mayflies emerge from their larval stage to swarm, it is called a bloom. These blooms are a sign of healthy aquatic ecosystems within the Order Ephemeroptera.

Physical Differences

Wings and Tails

Fishflies and mayflies share some similarities, but they differ mainly in their wings and tails. Both adult mayflies and dragonflies have two pairs of wings, but mayflies have larger, triangular front wings and smaller, round hind wings¹. On the other hand, adult fishflies, like dobsonflies, have two pairs of equal-sized wings². Mayflies also have long tails with two or three filaments³, while dragonflies and fishflies have short cerci⁴.

Mayflies:

• Two pairs of wings (triangular front wings and smaller, round hind wings) ⁵
• Two or three long tail filaments ⁶

Fishflies:

• Two equal-sized pairs of wings ⁷
• Short cerci ⁸

Gills and Abdomen

Mayfly nymphs possess gills along their abdomens, which help them respire underwater ⁹. Fishflies also have gills, but they are found on the thorax of their larvae¹⁰. The adult stages of both insects do not have gills. Another difference is mayflies tend to have delicate, elongated bodies, while fishflies have more robust bodies.

Mayflies:

• Gills on abdomen (nymphs only) ¹¹
• Delicate, elongated bodies ¹²

Fishflies:

• Gills on thorax (larvae only) ¹³
• Robust bodies ¹⁴

Eyes and Antennas

Both mayflies and fishflies exhibit differences in their eyes and antennas. Adult male mayflies have large, compound eyes that facilitate mate searching¹⁵, while adult female mayflies have smaller eyes¹⁶. In contrast, fishflies, like dobsonflies, have smaller, more evenly sized eyes¹⁷. Furthermore, mayflies have short, bristle-like antennas¹⁸, while fishflies have longer, more conspicuous antennas¹⁹.

Mayflies:

• Large, compound eyes (male) ²⁰
• Short, bristle-like antennas ²¹

Fishflies:

• Smaller, evenly sized eyes ²²
• Longer, conspicuous antennas ²³

Ecological Role and Impact

Aquatic Insects and Water Quality

Mayflies and fishflies, both aquatic insects, significantly contribute to water quality. They serve as indicator species, with their presence representing healthy freshwater ecosystems. These insects play a crucial role in the following processes:

• Breaking down organic matter
• Recycling nutrients within aquatic environments
• Maintaining balanced water ecosystems

Feeding Habits and Impact on Ecosystem

Mayflies:

• Primarily feed on algae, dead leaves, and living plants in their nymph phase
• Directly affect the freshwater ecosystem by controlling algal populations
• Contributes to nutrient cycling and food chains

Fishflies:

• Also known as chauliodes rastricornis
• Carnivorous, preying on smaller aquatic insects
• Contributes to the natural balance by maintaining insect populations and nutrient cycling

The different feeding habits of mayflies and fishflies help establish a harmonious food chain and nutrient balance within aquatic ecosystems.

Fishflies and Mayflies as Prey

Both mayflies and fishflies serve as crucial prey for a variety of freshwater vertebrates, particularly fish. Notable examples include trout, which consume mayfly nymphs in a feeding strategy known as the “drift.” Additionally, anglers imitate mayflies as bait, known as “shadflies” or “up-winged flies.”

A comparison of fishflies and mayflies can be summarized in the table below: