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Bug of the Week: Thurber’s Cotton and Ants

Yesterday we introduced the lovely plant, Thurber's cotton, Gossypium thurberi.

While I was taking photographs of the plant, I noticed some ants.

ant-on-flower-petal-2These kind of ants are called rover ants. They are not very big. What are they doing on the plant?

ant-visiting-floral-nectaryHere's one in the flower. It is visiting the nectar-producing area or "floral nectary."

ants-at-EFNs-darkThe rover ants were also visiting an area under the flowers, on the sepals. Any ideas why?

ant-visiting-EFN-33Having some experience with cotton plants, I  realized the ants were visiting some nectar-producing areas there as well. Nectaries outside the flower proper are called "extrafloral nectaries." See that dimpled area the ant is facing? That is an extrafloral nectary.

ants-at-EFN-multipleAs you can see, the extrafloral nectaries on the plant were very popular.

Many different plants produce nectar in various extrafloral nectaries and most of them attract ants and small wasps.

The most commonly-reported reason that plants have these structures is that the nectaries attract predators and parasites, which in turn attack the eggs and larvae of plant-feeding insects they encounter.

Have you ever seen ants visiting nectaries on plants? What kind of plant was it?

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