Insect & Pests

All Insect & Pests Content
Gray beetle with long antennae that are alternating white and black pattern on green leaf petiole.

Dectes Stem Borer May Be More of an Issue During 2021

Dectes stem borers are an annual pest of sunflower in South Dakota. During most years, they do not cause major issues in sunflower. However, we have observed increased issues with this pest during dry years.

Small, black beetle with a long snout.

Headclipping Weevils in Sunflower

Headclipping weevils have been active in some sunflower fields and in ornamental sunflower throughout South Dakota. Although the headclipping weevil is considered a minor pest of commercial sunflowers, it can cause a lot of problems for individuals trying to maintain sunflowers in their yards and gardens.

Green and brown grasshoppers on the leaves of a sunflower plant.

Grasshoppers Already Moving Into Sunflower Fields

With grassland food sources being depleted earlier than usual due to drought, grasshoppers are moving into nearby crops in search of vegetation. In parts of western South Dakota, grasshopper nymphs have already been observed feeding on young sunflower plants.

Corn silks with a beetle on them.

Redheaded Flea Beetles Clipping Silks

This week, redheaded flea beetles were observed in corn. Redheaded flea beetles will often strip only a layer of the leaves off corn, which results in windowpane holes, but the bigger issue is that they will also feed on corn silks.

A large wasp on a pink flower.

Cicada Killer Wasps Are Active in South Dakota

The cicada killer wasps are active in South Dakota, which means cicadas are probably not far behind. As their name implies, cicada killer wasps use cicadas as a food source. They can present an impressive spectacle if you observe one carrying a paralyzed cicada from a tree.

Light colored fly with dark pattern on wings sitting on a green leaf.

Sunflower Receptacle Maggot Flies Spotted in Sunflower

Quite a few sunflower receptacle maggot flies have been spotted in South Dakota sunflower fields. The adults don’t feed on sunflower, but the larvae of this insect are considered minor pests of South Dakota sunflower.

Caterpillar with a red stripe on its back sitting on a green leaf. Bottom: Mottled gray caterpillar sitting on a green leaf.

Cutworms in Sunflowers

In South Dakota, some late-planted sunflower fields are having some cutworm pressure. Although most cutworm activity should be wrapped up by now, it is possible that some populations may have been feeding up until the beginning of July.

Green soybean leaf with small holes near the center and edges.

Redheaded Flea Beetles Active in Soybean

Redheaded flea beetles are active in soybean. Although they haven’t caused significant defoliation yet, their activity should be monitored.

Green caterpillar with a dark brown head.

Obliquebanded Leafrollers Active in South Dakota Soybean

If you’ve observed rolled soybean leaves that are held together by webbing, don’t immediately think thistle caterpillar. The obliquebanded leafroller caterpillar will roll soybean leaves and hold the leaf in place with silken webbing.

Small, green teardrop shaped insects on a green, soybean stem with pink flower.

Soybean Aphids Spotted in South Dakota

Soybean aphid populations have been observed in South Dakota. Although these populations are still very small, it is a good reminder that soybean aphid scouting should occur throughout the growing season to prevent population outbreaks and yield loss.