Beans · Symptom guide
Bugs on bean plants
Bugs on bean plants in a garden bed are a look-and-compare job. Cited sheets list Mexican bean beetles as observations, not a ranked or confirmed cause. This page does not diagnose, name a spray, or sell a treatment.
Cited observations are comparisons—not a confirmed diagnosis. Check the cited sources and local requirements before taking action.
Save this bed. See it coming next year.
Your checks stay in the Field Book so next season is not a guess.
Illustrative photograph — not identification proof.
Look
Compare the plant in front of you with the cited notes after Other causes. Lacy leaves or small beetles alone do not name a cause on this page.
Other causes
Growing notes live on how to grow beans. Garden-wide looks live on garden pests. Tomato hornworm is a separate species page — not this crop-pest list.
What the sources say — at a glance
One source per card. Facts are not averaged.
Clemson HGIC 1302 (South Carolina)
Mexican bean beetles named on snap beans.
Details and limits (2)
Look
Clemson HGIC 1302 (South Carolina) names Mexican bean beetles on snap beans. Naming on that sheet — not a ranking and not a diagnosis.
Limit
South Carolina HGIC 1302. Naming-on-sheet only.
Clemson HGIC 2201 (South Carolina)
1/4–1/3 in, convex, yellow to coppery-brown. Eight spots. Underside feeding; lacy look.
Details and limits (3)
Look
Clemson HGIC 2201 (South Carolina): the Mexican bean beetle (Epilachna varivestis) is 1/4- to 1/3-inch long, very convex, and yellow to coppery-brown. Each wing cover has eight small, black spots that form three rows across the body. Observation — not a diagnosis.
Look
Clemson HGIC 2201 (South Carolina): both larvae and adults feed on the undersides of leaves, leaving the upper surface more or less intact. The larvae consume areas of leaf tissue, leaving veins between the chewed areas, which gives the leaf a skeletonized, lacy appearance. Observation — not a diagnosis.
Limit
South Carolina HGIC 2201. Observation only — not a treatment.
Maryland Extension (Maryland)
Maryland Extension (Maryland): host plants are legumes, especially lima and snap beans. Host as named — not a ranking.
Details and limits (5)
Host
Maryland Extension (Maryland): host plants are legumes, especially lima and snap beans. Host as named — not a ranking.
Look
Maryland Extension (Maryland): larvae and adults feed on the underside of leaves between the veins, removing the lower epidermis. The upper epidermis dies, producing a transparent, lacy look. Observation — not a diagnosis.
Method
Maryland Extension (Maryland): cover entire rows of beans with row cover after planting. You can leave the cover on until harvest. Method — not a prevention promise.
Method
Maryland Extension (Maryland): crush egg clusters, larvae, and adults by hand. Method — not an efficacy claim.
Limit
Maryland Mexican bean beetle sheet. Observation, host, and method as named.
Illinois Extension Good Growing (Illinois)
About 1/3 in, yellow to coppery brown, 16 black spots. Yellow egg clusters.
Details and limits (2)
Look
Illinois Extension Good Growing (Illinois): Mexican bean beetle adults are round-to-oval, hard-bodied insects, about 1/3 inch in length, yellow to coppery brown, with 16 black spots. Females lay clusters of yellow eggs on the undersides of leaves. Observation — not a diagnosis.
Limit
Illinois Good Growing post. Observation only.
UMN Extension (Minnesota)
No Mexican bean beetle note on this page.
Details and limits (2)
Look
Minnesota's growing-beans page does not provide a Mexican bean beetle note for this page.
Limit
Minnesota growing-beans page. Absence as stated.
Sources differ
Make it yours
Save the bed in the Field Book so next season is not a guess.
How we know — methodology. Ranges and assertions are cited per source, not blended.