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Section 26.6.6: Sap Beetle

Also known as Picnic Beetle

Time of concern: Ear fill through harvest
Key characteristics: Beetles of the predominate species are black, about 3/8 inch long, and have two, reddish orange spots on each wing. They are frequently found in leaf axils and ear tips and often infest ears previously damaged by worms or birds. The larvae, which are small, white, and maggot-like may also be found at the ear tip. 

Management Option Guideline
Scouting/thresholds

Inspect ears of corn to determine if sap beetles are present. No thresholds are available. See Reference 3.

Fresh Market Sweet Corn IPM Scouting Procedures

Natural enemies

The species and effect of natural enemies is unknown. 

Note(s) Sprays for worm pests generally minimize the threat of sap beetle infestations. In general, all pyrethroids used against worm pests are effective against sap beetles.
Resistant varieties Avoid varieties with short husks or poor tip cover.
Site selection Dispose of breeding sites (e.g. decaying fruit) in vicinity.
Postharvest Clean cultivation is recommended because beetles overwinter in crop residue. It is especially important to destroy or remove infested ears of corn.
Insecticide Resistance Management

The Insecticide Resistance Action Committee (IRAC) has classified insecticides into resistance management groups. Most insecticides include an IRAC group number on the front page of the label. Alternating between insecticides with different group numbers will help avoid the development of resistant insect populations.

Crop rotation and
Sanitation
These are not currently viable management options.
Pesticides Cornell Integrated Crop and Pest Management Guidelines for Commercial Vegetable Production