Toxorhynchites rutilus, also known as the elephant mosquito or treehole predatory mosquito, is a species of mosquito in the family Culicidae. Unlike most species in the genus that populate the tropics, Tx. rutilus is endemic to temperate regions. As their name suggests, these mosquitoes commonly lay their eggs in treeholes where their larvae are predators on a variety of arthropods. As with other mosquitoes, they also inhabit other bodies of stagnant water such as in a tire or artificial containers. but not large bodies of water like ponds and ground pools. Females are able to strategically locate breeding sites that already contain prey to oviposit in.

Tx. rutilus feeding behaviors make them strikingly different from a typical mosquito. Both adult males and females are strictly nectar-feeding and so they do not have a role in the transmission of pathogens to animals as in other mosquitoes. Instead, their larvae are predacious and could potentially help curb the spread of diseases via vector mosquitoes. While they commonly prey on copepods, rotifers, ostracods, and chironomids, they also generally have a preference for certain species of mosquito larvae including common disease vectors such as Aedes albopictus, Aedes aegypti, and Aedes polynesiensis. If their habitat lacks food or is overcrowded, the larvae are known to succumb to cannibalism. Their larval feeding preferences make them of special interest to biological control scientists and entomologists. There have been few successful instances of using Tx. rutilus as biological control in regions such as Hawaii, Florida, Louisiana, and Japan.

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