Caddisflies on the menu

February 19, 2013

With 150 species found in Ireland, occurring across a wide range of aquatic habitats, it is no surprise that members of the Order Trichoptera are on the menu for many insectivorous predators. In their aquatic larval stage, caddisflies are vulnerable to predation by many fish species. Caddisfly larvae have been shown to be an important element in the diet of juvenile salmon and trout in Ireland, and have also been recorded at varying levels in the diet of minnow, three-spined stickleback, eels, perch, roach and tench.

While life beneath the water provides caddisfly larvae with protection from most airborne predators, one bird has no problem stepping beneath the surface to find them. Caddisfly larvae form a large part of the diet of the Dipper, which captures its prey while wading and diving, even in fast-flowing river and streams.

Once the caddisfly larvae have metamorphosed and the adults make their way into the aerial realm, they leave the dangers of predation by fish behind (so long as they don’t become fish food in the short window between cutting their way out of the pupa and leaving the water surface), but once in the air they are exposed to further dangers. Most species of caddisfly time their emergence as adults to occur at night, so as to reduce the risk of predation by visual predators like fish. However, this leaves them vulnerable to nocturnal predators in the form of bats. Daubenton’s bats are strongly associated with water, and caddisflies form a large part of the diet of this species. Both adults and pupal stages of caddisflies have been recorded during dietary analysis of this species, which suggests that Daubenton’s bats take prey from the water surface. Other bat species, including Leisler’s bat, also prey on adult caddisflies.

Further detail on the information in this post can be found in the following papers and the full references can be found on the References page: McCarthy, 1972, Daoud et al., 1986; 1985a; 1985b, Moriarty, 1972; 1973; 1974a; 1974b, Gargan & O’Grady, 1992, Kennedy & Fitzmaurice, 1970, Agnew & Perry, 1993, Taylor & O’Halloran, 1997; 2001, Flavin et al., 2001, Shiel et al., 1998.

If you have any more references for predators of caddisflies at any life-stage, please let me know.

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