Spiders of the genus Argyrodes (Theridiidae), also called dewdrop spiders, occur worldwide. They are best known as kleptoparasites:
they steal other spiders' prey. They invade and reside
in their host's web even though they can spin their own
However, the relationship can sometimes be commensal or
even mutual since the dewdrop spider can feed on small
trapped insects that are not eaten by the host.
Some species can even prey upon the host. Many species are black with silvery markings. Most species are relatively small. For example,
A. incursus has a body length of 3–4.5 mm while A. fissifrons has a body length of about 12 mm.
The Dew Drop Spider is a tiny spider and has a conical abdomen that is mostly silver in
colour. In Australia it is often found sharing the web of the much larger spiders such
as the Golden Orb Weaver (Nephila sp.) and Garden Orb
Weaver (Eriophora sp.). They shine like drops of dew in
the large web of the Orb Weaver. They build their small egg sacs near the edge of the Orb Weaver's web.
The Dewdrop Spider is also known as the Quicksilver Spider because of their bright silver abdomen, however these are minute spiders, being no larger than a match head and so are not noticed unless sought. Small size can nevertheless still be an advantage in making a living, for these are kleptoparasitic,
which means parasitism by theft and they live
permanently as a parasite in the webs of large
orb-weaving spiders but they will also occupy other spiders webs. What the Dewdrop Spider seek are large permanent webs made by large docile spiders.
These small spiders actually do the large spiders (whose web they cohabit) a favour by keeping the web clean of tiny flying insects that are much too small for the larger spider to be bothered with, however the dewdrops are not too timid to take a share of the larger spiders meal and will even partake at the same time. The dewdrop spider is quite communal and webs can be occupied by several individuals, but being so small, having others on relatively vast webs that can stretch for 2-3 metres, any disruptive interaction over territory is probably unlikely.
Here's some photos sent in by