Tiny Yellow Sawfly - Ask Extension
Hi. I have fringed loosestrife in my yard that has been eaten pretty heavily over the last 2 summers (and it's starting again). Today, as I was digg...
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Tiny Yellow Sawfly #406419
Asked June 12, 2017, 12:03 PM EDT
Hi. I have fringed loosestrife in my yard that has been eaten pretty heavily over the last 2 summers (and it's starting again). Today, as I was digging some out, I found tiny gray/blue caterpillars on the leaves, munching away. After some research online and further investigation with a magnifying glass, I believe I have Tiny yellow sawfly - Monostegia abdominalis on my plants.
Should I remove/kill these insects? I believe they are not native, so that seems to suggest yes, but I don't want to kill an insect that is a pollinator or has more benefits than drawbacks. Seeing the holes in the plants makes them look less appealing, but the monarch caterpillars chew holes in my milkweed and I'm delighted to see that.
Thanks for your help!
CarolAnn Hook
Dakota County Minnesota
Expert Response
Monostegia
abdominalis is
a type of sawfly which is found on plants in the primrose family, including
some loostrife. They are best controlled
by hand picking and dropping them into soapy water. You could spray with low
impact insecticides like horticultural oil or spinosad.
