The adults of several types of aquatic insects will frequently emerge in large numbers, causing concern among homeowners.
Mayflies have large forewings, small hindwings that are held together at rest over the body.
Stoneflies have a hindwing which is larger than the forewing, and the wings are held flat over the back. The adults of these insects are generally short lived, especially in the case of the mayflies, and they generally do not feed. Even though homes near aquatic habitats may be covered with resting insects during mass emergences, expensive chemical controls are seldom necessary. The insects can be allowed to disperse naturally, or they can be removed by sweeping or vacuuming. Those insects which get indoors can be subdued with an aerosol flying insect spray containing pyrethrin, and then removed.