Argyrodes, also called dewdrop spiders, is a genus of comb-footed spiders that was first described by Eugène Louis Simon in 1864.[1] They occur worldwide, and are best known for their kleptoparasitism. They can spin their own webs, but tend to invade and reside in their hosts' webs.[2] This relationship can be commensal or even mutual if the dewdrop spider feeds on small trapped insects that are not eaten by the host.[3] Some species can even prey upon the host.[2]
The genus name is a combination of the Ancient Greek "argyros" (άργυρος), meaning "silver", and the suffix "-odes", meaning "like".[1]
Most species are relatively small, and many are black with silvery markings. A. incursus has a body length of 3 to 4.5 millimetres (0.12 to 0.18 in),[7] while A. fissifrons has a body length of about 12 millimetres (0.47 in).[3] The body has a characteristic conical or triangle shape with a shorter third pair of legs, common in web dwelling spiders.[8] The silver coloration of Argyrodes may be able to attract moths and other insects as it stimulates their photoreceptors and may resemble starlight.[9]
Most Argyrodes are found in the tropics, though fifteen species are found in the United States.[2] A. elevatus is found in the southern US, A. nephilae in Florida and A. pluto in Maryland, Virginia, and Missouri. The latter species has been reported as far south as Chihuahua and Jamaica as well.[10]
Argyrodes are kleptoparasitic spiders that live on the webs created by orb-weaver spiders. These spiders feed on the small prey items caught in the host webs that they parasitize. In some instances, Argyrodes may even feed on previously digested carcasses that remain on the web.[11] While these spiders are well known for being kleptoparasitic, they are also arachnophagous, meaning they prey on other spiders. Argyrodes will wait for a time when the host spider is vulnerable, such as during molting, and will attack and feed on it. This is true for the host spider's offspring as well, however Agyrodes will only feed on other spiders in some instances.[12]
It has been suggested that Argyrodes may have a mutualistic relationship with the host. The silver coloration of Argyrodes was found to attract more prey, particularly moths, to the host's web. This allows for larger prey items to be attracted for the host spider while Argyrodes is able to consume the smaller unwanted prey.[9] A common misconception about Argyrodes is that it steals prey from the host spider, but recent research has showed that Argyrodes rarely steals large prey items from the host, and only eats what the host spider typically does not want.[9] They have been noticed in complex Joro spider webs, for example.[13]