Syrphid Flies in Corn

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Figure 1. Syrphid Fly Larvae. Photo Credit: John Obermeyer, Purdue University.

• There are several reports of syrphid fly larvae in corn
• Syrphid fly larvae are not pests. They are beneficial predators that feed on corn leaf aphids
• Syrphid fly is also known as a Hover Fly and often called Corn Flies or Sweat Bees
• Although they resemble bees, they are a true fly and do not bite or sting

We have gotten several calls recently about ground rigs applying corn fungicide that are covered in larvae and wondering if it is an insect pest that needs to be controlled. Fortunately, it is not a pest, it is syrphid fly larvae. Corn leaf aphids have been found in low to moderate levels this year and this is likely why syrphid fly populations have spiked recently. Syrphid flies, also known as Hover Flies, are beneficial insects with complete metamorphosis. Adult syrphid flies feed on pollen, nectar, and honeydew from aphids. The adults can be distinguished from bees by inspecting the wings. Syrphid flies have one set of wings and bees have two sets of wings. The adult females lay hundreds of eggs on leaves near aphid colonies. The larvae are predators that feed on aphids and a single larvae can consume up to 400 aphids in its life cycle. Larvae have tapered bodies that resemble slugs. 

Be sure to take note of syrphid fly larvae populations when scouting for corn leaf aphid.

Figure 2. Syrphid Fly adult on a corn tassel. Photo Credit: John Obermeyer, Purdue University.

Sources: 

NC State Extenstion - https://content.ces.ncsu.edu/syrphid-flies

University of Minnesota Extension https://extension.umn.edu/beneficial-insects/syrphid-flies#sources-3147110

Related Categories: Corn, Insects, Syrphid Flies, Hover Flies, aphid predators.