Net Spinning Caddisflies

by Kelsey Laymon, Research Scientist

Fire 1: Example of Hydropsychidae Net
Fire 1: Example of Hydropsychidae Net

One of the coolest things I have come to learn while working at Phinizy Center is the life cycle of the net spinning caddisfly larvae. These aquatic insects reside in the family of Hydropsychidae and occupy freshwater systems. Usually positioned at the large end of their retreats, the Hydropsychid spin an elaborate net or sieve made of silk, which is similar to that of a caterpillar. These nets are constructed to catch their food, which consists of algae, small invertebrates and detritus. Different types of caddisflies will spin different mesh sizes and shapes based on which type of food they are targeting.

Figure 2: Hydropsychidae Caddisfly
Figure 2: Hydropsychidae Caddisfly

To collect what they have caught in their nets, some genus like Macrostemum, will utilize their hairy forelegs and hairy mouth parts. The hair collects while they walk over the net and then they are able to eat it. Most caddisflies in Hydropsychidae need flowing current to capture food, however caddisflies in another genus, Neureclipsis can utilize weak flowing water by building a large cornucopia shaped net and eating what collects at the smaller end.

Figure 3: Cornucopia Shaped Net of Neureclipsis on Bottom Right
Figure 3: Cornucopia Shaped Net of Neureclipsis on Bottom Right

Another interesting aspect of caddisflies are that some species can actually produce a sound by rubbing their femurs across their heads, just like a grasshopper rubbing its back legs together. This noise is used as a defense from other caddisflies that might try to steal their net retreats. Caddisflies that don’t have a retreat will try to seek out already built retreats and the sound will warn foes that the retreat is already occupied. These amazing creatures make their own silk, build their own nets to capture food and create underwater noises! Learn more about them here.

References:

http://snre.umich.edu/cardinale/wp-content/uploads/2012/04/cardinale_func_ecol_2004.pdf

http://steonline.org/circles/lessons/energy/PDFs/water-pixies12.pdf

https://www.researchgate.net/profile/James_Wallace18/publication/251760140_The_Role_of_Filter_Feeders_in_Flowing_Waters/links/544901860cf2f14fb81459d2.pdf

http://www.ephemeroptera-galactica.com/pubs/pub_m/pubmerrittr1981p132.pdf