I was excited to see there was leafcutter bee activity on my walk at Toledo Botanical Garden earlier this week. The activity was on a redbud (Cercis canadensis) seedling. I observed the activity occurred on the lower leaves, closest to the ground. I also noticed leaf cutting bee activity on a redbud at home, and again the activity was near the ground.
Most of the common leafcutter bees (Megachile spp.) are similar in size to the common honeybee, usually a little darker with light bands on the abdomen. Their actions or habits differ from the common honeybee too. It is important to note that leafcutter bees are not aggressive, and sting only when handled. The activity resulting in the injury that I saw was created earlier in the season.
Leafcutter bees are solitary bees, and don’t produce colonies like social insects such as honeybees and yellowjacket wasps do. Female leafcutter bees do all the work of rearing. This includes digging out nesting areas, creating nest cells and providing their young with food. Adult females can live up to two months and typcially lay between 35 to 40 eggs during this time.
Once the nest is made, the leafcutting bees collect fragments of leaves to construct individual cells within the nest. The bees cut leaves in a distinctive manner, making a smooth semicircular, or cresent moon shape, cut about 3/4 inch in diameter from the edge of leaves. Although they cut many types of leaves, Dr. Whitney Cranshaw listed rose, green ash, lilac and Virginia creeper as some favorites in a Factsheet from Colorado State University. He goes on describing this injury as a minor curiosity. However, where leafcutter bees are abundant and concentrate on cultivated plantings, the removal of leaf tissues can result in some stress on the plant, although chemical treatmens are not receommend.
Leafcutter bees do not actually eat the cut pieces of leaves that they remove. Instead, they carry them back to the nest and use them to fashion nest cells within the previously constructed tunnels.
While you are enjoying this beautiful summer-like weekend, take a peak around and see if you see any leafcutting bee activity in your landscape or at a park or along a walking trail. You might be surprised what you see.