Sialis is a genus of aquatic insects commonly known as alderflies. These insects are found near creeks and rivers. They have a distinct appearance with a long, narrow body and long legs. If you are looking for synonyms for this word, some of the alternatives you can use are alderfly, dobsonfly, or hellgrammite. These words are used interchangeably to describe these aquatic insects. They belong to the order Megaloptera, which means "big wings" and it refers to the large, transparent wings that these insects possess. So, whether you are a nature enthusiast or simply curious about insects, these words will come in handy to describe these amazing creatures.