''Arcola malloi'' (formerly ''Vogtia malloi'') is a species of

snout moth The Pyralidae, commonly called pyralid moths, snout moths or grass moths, are a family of Lepidoptera in the ditrysian superfamily Pyraloidea. In many (particularly older) classifications, the grass moths (Crambidae) are included in the Pyralida ...

known as the alligator weed stem borer. It is used as an agent of

biological pest control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...

against the noxious

aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

known as

alligator weed ''Alternanthera philoxeroides'', commonly referred to as alligator weed, is a native species to the temperate regions of South America, which includes Argentina, Brazil, Paraguay and Uruguay. Argentina alone hosts around 27 species that fall with ...

(''Alternanthera philoxeroides''). This moth is native to South America. It was introduced to the United States in the 1970s to attack the alligator weed. It is now established in populations of the weed in the southeastern United States. The adult moth is brown and an elongated arrowhead shape about 13 millimeters long. The female lays between 200 and 300 white eggs during her week-long adult life. The

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

is white when first emerged from its egg and quickly turns brown and striped. The larva bores into the stem of the alligator weed and consumes it from the inside out, generally destroying between four and eight stems before

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

ting. It pupates in a cocoon inside the hollowed-out stem for ten days. Alligator weed which has been attacked by the larva has areas of dead leaves distal to the point at which the larva has destroyed the stem, blocking nutrient flow. A mat of the weed can be quickly eliminated in heavy infestation. This moth and the alligator weed flea beetle may be found in a single mat of alligator weed; in this case, the two insects work in

synergy Synergy is an interaction or cooperation giving rise to a whole that is greater than the simple sum of its parts. The term ''synergy'' comes from the Attic Greek word συνεργία ' from ', , meaning "working together". History In Christia ...

and the weed rarely recovers.

References

* Coombs, E. M., et al., Eds. (2004). ''Biological Control of Invasive Plants in the United States''. Corvallis: Oregon State University Press, 146. Phycitinae Insects used for control of invasive plants Lepidoptera used as pest control agents Moths described in 1961 Moths of New Zealand Moths of South America {{Phycitini-stub