spring fishfly

(Chauliodes rastricornis)

Conservation Status
spring fishfly
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

     
  Minnesota

not listed

     
           
           
           
           
           
           
           
 
Description
 
 

Spring fishfly is a large, short-lived, primitive-looking, winged insect. It occurs in the United States and southern Canada east of the Great Plains. It is common in Minnesota. Larvae are found in a variety of aquatic habitats, including ponds, swamps, marshes, and springs. They take one to five years to reach maturity. They feed on both algae and small invertebrates, including crustaceans, clams, worms, and other insects. Adults are found from late May to early July near larval habitats. They live only a few days to a week. They are active at dusk but remain hidden during the day. It is thought that they do not feed, though they have been collected in moth traps.

Adults are brownish-gray, 1 to 2 (35 to 50 mm) in length, and have a wingspan of 2½ to 3 (63 to 80 mm).

There are two large compound eyes on the sides of the head and three small simple eyes (ocelli) in a triangle on top of the head. The antennae are long, dark brownish-gray, and have many segments. On the female they are serrated on one side, with a short, saw-like tooth on each segment. On the male they are comb-like, with a long branch on one side of each segment (pectinate). The mouthparts are adapted for chewing. The jaws (mandibles) on both sexes are always shorter than the length of the head. The back of the head (occiput) is brownish-gray with dark brown to black markings. On each side of the occiput there is a blotchy stripe in the middle (middorsal), a stripe on each side, and four short streaks between.

The thorax has three segments. It is brownish-gray with dark brown to black markings and a few small yellow spots. The first segment (prothorax) is rectangular and slightly narrower than the head. It is brownish-gray above with dark brown to black markings, including a large dark spot on each side.

The abdomen has ten segments. When viewed from the side the anal plate on the last segment is triangular.

The wings are delicate and very long, much longer than the body. They are clear and tinted pale brown, with no dark or white markings apart from the veins. The veins on the forewing are dark interrupted with white, appearing irregularly dashed. There are many slender cross veins near the leading edge (costal area). The media (M) vein has two branches, both of which reach the wing margin.

The hindwings are pleated, allowing them to be folded over the abdomen when at rest. The veins are mostly medium brown. Only the vein on the leading edge (costal margin) is dashed dark and white like the forewing.

The legs may be mostly yellowish or entirely dark. The last part of the leg (tarsus), corresponding to the foot, has 5 segments and is always dark. The The fourth tarsal segment is cylindrical, not dilated.

 
     
 

Size

 
 

Total Length: 1 to 2 (35 to 50 mm)
Wingspan: 2½ to 3 (63 to 80 mm)

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

A variety of aquatic habitats, including ponds, swamps, marshes, and springs

 
     
 
Biology
 
 

Season

 
 

Late May to early July

 
     
 

Behavior

 
 

Adults are active at dusk but remain hidden during the day. The wings are held roof-like and to the side of the abdomen when at rest. They are relatively weak fliers.

 
     
 

Life Cycle

 
 

The larva takes 1 to 5 years to reach maturity. After reaching maturity, it crawls onto land and pupates in moist soil under a log or rock. Adults emerge in the spring and live only a few days to a week.

 
     
 

Larval Food

 
 

Algae and small invertebrates, including crustaceans, clams, worms, and other insects.

 
     
 

Adult Food

 
 

Adults do not feed.

 
     
 
Distribution
 
 

Distribution Map

 

Sources

7, 24, 27, 29, 30, 82.

 
  2/14/2021      
         
 

Occurrence

 
 

Common in Minnesota

 
         
 
Taxonomy
 
 

Order

Megaloptera (alderflies, dobsonflies, fishflies)  
 

Family

Corydalidae (dobsonflies and fishflies)  
 

Subfamily

Chauliodinae (fishflies)  
 

Genus

Chauliodes  
       
 

 

 
       
 

Synonyms

 
 

Hermes indecisus

 
       
 

Common Names

 
 

spring fishfly

toothed-horned fish-fly

 
       

 

 

 

 

 

 

 

Glossary

Costal margin

The leading edge of the forewing of insects.

 

Occiput

The back of the head. In Odonata, Megaloptera, and Neuroptera, the upper part of the head behind the eyes.

 

Ocellus

Simple eye; an eye with a single lens. Plural: ocelli.

 

Tarsus

On insects, the last two to five subdivisions of the leg, attached to the tibia; the foot. On spiders, the last segment of the leg. Plural: tarsi.

 

 

 

 

 

       
Visitor Photos
   
Share your photo of this insect.
 

This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach one or more photos and, if you like, a caption.

       
       
MinnesotaSeasons.com Photos
   

Male

  spring fishfly    
       
       

 

Camera

     
Slideshows
   
     
     
     
     

 

slideshow

       
Visitor Videos
       
Share your video of this insect.
   

This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach a video, a YouTube link, or a cloud storage link.

       
       
Other Videos
 
  Spring Fishfly (Chauliodes Rastricornis)
Random Bugs I Find
 
   
 
About

Apr 1, 2019

   
       
  Spring Fishfly (Corydalidae: Chauliodes rasticornis) Female
Carl Barrentine
 
   
 
About

Jul 23, 2011

Photographed at the Turtle River State Park, North Dakota (22 July 2011). Thank you to Brady Richards (@Bugguide.net) for confirming the idenity of this specimen!

   
       
  Chauliodes rastricornis
DocBebitte
 
   
 
About

Feb 9, 2017

Femelle C. rastricornis. Female C. rastricornis.

Québec (QC), juin 2015/june 2015.

Voir/See: https://docbebitte.com/2017/02/11/chauliodes-un-peigne-ou-un-rateau/

   
       

 

Camcorder

         
Visitor Sightings
   
Report a sighting of this insect.
This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Be sure to include a location.

     
     
 
MinnesotaSeasons.com Sightings
         
         

 

 

Binoculars


Created: 2/15/2021

Last Updated:

About Us | Privacy Policy | Contact Us | © 2021 MinnesotaSeasons.com. All rights reserved.