| Leaf-cutter Ant (Acromyrmex octospinosus (Reich, 1793)) |
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Scientific name: Acromyrmex octospinosus (Reich, 1793) Common name: Leaf-cutter Ant French name: Fourmi-manioc, Fourmi coupe-feuilles. Order: Hymenoptera Family: Formicidae Wingspan : Large worker: more than 1 cm. Small worker: less than 4 mm. Biotope: Tropical forests. Geographic area: From southern Mexico in Central America to Venezuela in northern South America. Introduced to several Caribbean island, including Cuba, Trinidad and Guadeloupe in the 1950's. Observation period : All year long. |
There are two genus of Leaf-cutter ants, the Atta genus and the Acromyrmex genus. Ants of the Atta genus have three pairs of spines on the thorax and first abdominal segment and a smooth exoskeleton while ants of the Acromyrmex genus have four pairs of spines and a rough exoskeleton. The ground colour of Acromyrmex octospinosus may vary from yellow brown to red. It differs from ants of the Atta genus by numerous little spines on the upper side of the head while ants of the Atta genus have only two. The shape of the spines is used to differentiate the species of the Acromyrmex genus. Acromyrmex octospinosus shows flat spines at the back of the pronotum with rounded tips. The median spines are missing. These ants cut pieces of leaves and plants and carry them to the nest. They store them in gardens where they grow fungus. They feed on the tiny white fruiting bodies of this fungus. They can be considered as pests because of the damages caused to plants. |
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A tourist, met on the foot track leading to the Saut de la Lézarde site, has shown me these Leaf-cutter Ants walking following each other. They were carrying pieces of plants. The identification of Acromyrmex octospinosus species is based on the fact that I have read that this is the only leaf-cutter ant species found in Guadeloupe. |
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I have shot this picture on the Îles du Salut (Islands of Salvation in English, in fact on the Île Royale). The four pairs of spines on the thorax and first abdominal segment indicate the Acromyrmex genus. We will stop at the genus identification. Telling the species apart requires an analysis of the shape and size of the different pairs of spines. I am not sure that the quality of the picture is enough for this. |
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We sometimes wonder how the leaf pieces are kept in balance. |
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This ant without any leaf has been found by chance in a corner of the picture. I have only seen it later on the computer. Is this one large worker in charge of cutting leaves? |
André Bon April 2014