Creepy Loosestrife Sawfly

Much to my dismay I was not happy to see that my patch of ground cover Lysimachia nummularia – Golden Creeping Jenny has been devoured by the Creepy Loosestrife Sawfly.  Sawflies are actually a non-stinging wasp that can do some damage on some of our ornamental plants.  Luckily enough for me my creeping jenny will grow back.

If you are not familiar with creeping jenny it’s a versatile perennial ground cover that thrives in damp locations.  You will often see it in garden centers being sold as an annual for containers, as a pond plant for water gardens, and as a perennial ground cover.  The chartreuse/green foliage and small yellow flowers that appear early summer makes this a great plant to use in full sun or partial shaded locations.

However, now that the creepy loosestrife sawfly has taken up resident in my patch of creeping jenny I am going to have to decide what to do.  From the literature that I’ve read the sawfly has up to two generations a year.  This means that my plant is going to continue to be munched on all season.  Because I am using this plant as a living mulch around my perennials I am hesitant to use any systemic products.  Contact insecticides such as carbaryl and pyrethroids will help manage this pest.  I can also cultivate the soil early fall to bring the overwintering pupa to the soil surface to let the winter’s cold take care of them.  I have some low impact options but right now I am stuck with half eaten ground cover under my mailbox.  What an eyesore!

Scott Evans
Scott Evans is a horticulture assistant with Nebraska Extension in Douglas-Sarpy Counties. A certified arborist through International Society of Arboirculture and Nebraska Arborist Association. Scott is also Tree Risk Assessment Qualified through ISA. Scott co-leads the Master Gardener program in Douglas & Sarpy counties. Along with volunteer management he provides his expertise with disease and insect identification, lawn and landscape weed management, plant health, and I.P.M. practices. He also enjoys growing many houseplants ranging from African violets to cacti and succulents. Scott has two Bachelors of Science, one in Biology (emphasis in Botany, Ecology and Environmental Science) and second in Environmental Geology from Northwest Missouri State University. He earned his Master of Agriculture from the University of Nebraska-Lincoln.

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