Yes, adult dobsonflies are rare. Throughout most of their lives, they remain in their larval form, known as hellgrammites. Hellgrammites go through four life cycle stages: eggs, larvae, pupae, and adult dobsonflies. The eggs hatch in two to three days, and the larvae remain completely aquatic during this stage, molting 10 to 12 times and remaining as larvae for one to five years. Once the larvae are fully grown, they pupate and settle in a wet, cool place near the water body. The pupal stage lasts two to four weeks, after which the adults emerge. Adult dobsonflies are even larger than hellgrammites and have glassy wings with conspicuous veins. Despite their long lifespan, dobsonflies live a very short time as adults.