Wednesday, October 15, 2014

Life in a Goldenrod

While examining goldenrod for head galls, I noticed one of the heads which had rolled up leaves. These weren't the tight clustered leaves of the goldenrod head gall shown last week.  They remained green and flexible.

Aphids in rolled leaves
All of the rolled leaves contained lots of frass (insect poop) and many had 10 to 30 aphids clustered together.  There were scattered juveniles in the cluster, a real family affair.


A few of the leaves also had green larvae nestled in the frass.  When I removed two of the larvae, each had an aphid attached which I could pull away with my fingernail.  I sent the pictures to Chris Barnhart who identified them as syrphid fly larvae which feed on aphids.

Syrphid fly larva with an aphid.
Syphrid flies are also known as hover or flower flies, named for their habit of hovering over flowers while nectaring.  Their larvae may be saprophytic, feeding on dead plant and animal material but some species are insectivores, eating aphids and other small plant eating species.  Some species are important as pollinators and others have commercial pest control value.
"Larvae of predaceous species feed on aphids and other soft-bodied insects and play an important role in suppressing populations of phytophagous insects. Larvae move along plant surfaces, lifting their heads to grope for prey, seizing them and sucking them dry and discarding the skins. A single syrphid larva can consume hundreds of aphids in a month."
Aphid lunch

All of this simply demonstrates that there is a lot more life in a goldenrod than initially meets the eye.

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