Every morning, while driving to work along King's Mill Pike I pass a stretch where numerous Catalpa trees grow. Realizing that their bloom cycle was drawing to a close, I finally took the time to pull over, smell the fragrant blossoms and snap a few photographs.
Catalpas typically grow to 40 to 60 feet tall and 20–40 feet wide. A 10-year-old sapling will stand about 20 ft tall. They can be recognized by their large heart-shaped leaves and showy white orchid-like flowers. In the autumn they sport 8 to 20 in long seed pods containing numerous small flat seeds, each seed having two thin wings to aid wind dispersal
Due to their large leaf size, Catalpas provide very dark shade and are a popular habitat for many birds, providing them good shelter from rain and wind. These trees have very little limb droppage, but drop large, dark brown bean pods during late summer. The wood of catalpas is quite soft.
Catalpa trees are the host plant for the Catalpa sphinx moth which has two or more generations each year. The caterpillars can completely strip catalpa trees and grow to three inches in length.
This photo shows late stage caterpillars. The back is velvet black upon molting. As they feed and expand, they lighten in color. Infestations rarely last more than two years in a row thanks to a parasitic wasp that attacks the caterpillars. This reduces damage to the trees as the caterpillars eat voraciously. Parasitized individuals will be covered with white cocoons. Just think of these insects as the tomato horn-worms of the catalpa trees and you will have the idea.
Catalpa worms are renown as great fish bait, especially for when going for catfish. Bait shops will pay a premium for them. The tree is at times dubbed the fish bait tree and anglers have been known to grow catalpas just for the bait potential, even going so far as to harvest and freeze caterpillars for future fishing expeditions.
Catalpa trees and picture-perfect lawns just don't mix particularly well, so it is not a frequent part of home landscapes these days. Part of the tree's lowly reputation is caused by the succession of lawn messes it creates. If it is not shedding leaves, it is dropping flower petals or long cigar-shaped seed pods. Those large green caterpillars create a lot of frass as they devour the tree leaves.
For now, I will just stop along that stretch of King's Mill Pike on occasion and enjoy the scent and beautiful blossoms of the roadside catalpas.