by Karl Blankenship

Caddisflies are a tolerant lot. As a rule of thumb, they tend to put up with more pollution than the stoneflies and that anglers often associate with high-quality streams. It is a tolerance bred from diversity; and, of the three major groups of aquatic , none is as numerous as the caddisfly.

Medium dark-olive sedge (Macronema zebratum) photo-David H. Funk

20 Pennsylvania Angler & Boater www.fish.state.pa.us Giant red sedge ( scabripennis)

photo-David H. Funk

The numbers say it all. Pennsylvania has 134 species of will help identify, and protect, particularly valuable stream stoneflies and 230 species of mayflies. But it has at least systems. With statewide inventories, people in the future 320 species of caddisflies, according to surveys compiled by will be able to track how aquatic populations–which Edwin Masteller, a professor emeritus of biology at Penn are critical to the aquatic food chain–are faring. Declines of State, Erie. (Only Alabama has more caddisflies, with 342.) certain species, or a change in the diversity Even that figure probably leaves some species uncounted. “I found in a particular stream, could be a signal that some- am sure there are more,” Masteller said. “I cannot cover all thing is wrong in the environment. of the diverse habitat in the state, and if others look, we will Though typically considered moderately tolerant of pol- find more.” lution, some caddisfly species are more sensitive than Indeed, between 1991, when he completed the first state- others, making them potential sentinels of water quality, wide survey, and 1998, when he updated it, the list grew by said Andrew Shiels, Fish and Boat Commission Nongame nine species. Masteller is encouraging others to join the and Endangered Species Unit Leader. “Some caddisfly spe- search: He has created a World Wide Web page where cies, I think, could be used as very good indicators,” he said. people can review results and report findings. One visitor to the site informed Masteller of a watershed where he col- lected 63 species of caddisflies over the course of a year, some of which are rare in Pennsylvania. The survey is not just an academic exercise. “This infor- mation could be used in evaluating high-quality watersheds and the need to protect or manage these areas,” Masteller said. “It may be useful in determining the streams for fish stocking. fishermen may be interested in the flight periods of certain species to coordinate their tying and subsequent trips.” Masteller’s work was backed by the Fish and Boat Com- mission and the Wild Resource Conservation Fund, which finances scientific and educational projects related to H. Funk photo-David Pennsylvania’s nongame wildlife. The Commission intends The larvae of many species build shelters, or cases, out of to incorporate information about caddisflies and other twigs, stones, bits of leaf, bark and other materials. aquatic insects into a computerized mapping system that They bind the parts together with a glue-like substance.

www.fish.state.pa.us Pennsylvania Angler & Boater 21 The design of each case is character- istic of a particular genus. Some “Some individual species are in cases are even portable. Some spe- more pristine waters and headwa- cies weave webs, attaching them to ter areas, while others are in areas rocks in fast-flowing streams, to that receive some silt.” catch food as it flows by. And then, Their ability to survive in many some species–typically the most areas reflects their strength in primitive–do neither. numbers. What’s true about After spending six to 10 months caddisfly diversity in Pennsylvania in the larval stage, caddisflies form is true throughout the continent. cocoons. Once transformed into a In North America, there are more Freeliving caddis, Ryacophila sp. , the insect cuts its way out of species of caddisflies–1,369–than the case–if it built one–and makes photo-David H. Funk of mayflies and stoneflies com- its way to the surface of the water, bined, making them an important where it breaks out of its pupal ex- insect species in almost every freshwater ecosystem. World- oskeleton and emerges as a winged adult. wide, there are an estimated 10,000 species of caddisflies. Adults have four wings of nearly equal length and are cov- Their great diversity stems from the fact that caddisflies ered with fine hairs; in fact, the Greek name for the have adapted to many habitat “niches” in waterways. Put caddisfly insect order, Trichoptera, means “hairy wings.” another way, some caddisflies tolerate poorer water quality When at rest, the wings are in an inverted “V” over the back, better than many and stonefly species. As one moves similar to a pup tent. The adults look like drab , and from pristine conditions, as a rule of thumb, the more im- tend to be poor fliers that are attracted to light. Collectors portant caddisflies become. often lure them into traps using black lights. Because mayflies, stoneflies, and caddisflies often serve as Like most aquatic insects, the caddisfly adult stage is the primary food for many forage and game fish species, the short, averaging only one to four weeks. Adults mate on tolerance of caddisflies–also known as sedges, shadflies, or streamside foliage, after which the females return to the wa- sandflies–can be particularly important for fishermen in ter to lay their . Some deposit eggs as they skim across many streams. “From that standpoint, in any marginal the surface. Others dive to the bottom where they attach trout water, you would be more likely to need imitations of their eggs to rocks or other submerged objects. Eggs usually caddisflies than mayflies,” said Greg Hoover, an entomolo- hatch within two to four weeks, and the cycle begins again. gist at Penn State. “If we were to rank those orders, Although this cycle has been going on for millions of stoneflies as an insect order are more sensitive than may- years, the significance of caddisflies to healthy stream sys- are, and third would be caddisflies.” tems has only lately been appreciated, which is why–nearly This tolerance to less-than-pristine conditions appears to three centuries after Pennsylvania was settled–aquatic in- be something caddisflies gained over time. The oldest, most sects are only now being comprehensively surveyed. When primitive species of caddisflies are those found in cool, comprehensive aquatic insect surveys began a decade ago, flowing streams. Today, many caddisfly species have caddisflies were chosen first, because of their diversity. adapted to other conditions; some are even found in ponds. “The caddisfly study was the building block to work with One family of caddisfly, the , have so many invertebrates to determine water quality in the Common- tolerant that some aquatic biologists consider them to be wealth,” said Frank Felbaum, Executive Director of the Wild the “white suckers” of the insect world. Still, that doesn’t Resource Conservation Fund. “Let’s face it, for years, we mean all species are tolerant; some are quite picky. In his have not conducted any kind of biological inventory in the surveys, Masteller found 51 state’s rivers on species other than caddisfly species that could be fishes.” found in no more than one county. Biologists have begun to consider Because of their diversity, the presence and diversity of many caddisflies also exhibit the greatest different types of organisms to fur- range of behavior among the three ther our knowledge of aquatic major aquatic groups. Caddisfly systems. Knowledge of the aquatic larvae are the engineers of the insects, molluscs, crustaceans, and aquatic world. Larvae of many fishes in a waterway helps us under- species build shelters, or cases, out stand habitat quality and its of twigs, stones, bits of leaf, bark, relationship to species diversity. or other materials, binding the parts together with a glue-like sub- Pycnopsyche sp. Dr. Edwin Masteller’s web site is at

stance. They often add to the cases photo-David H. Funk http://vibrio.bd.psu.edu/ecm/ as they grow, and eventually the ecmpage.html. cases become the shelters in which the larvae transform into pupae.

22 Pennsylvania Angler & Boater www.fish.state.pa.us