{"id":16601,"date":"2025-10-31T10:50:26","date_gmt":"2025-10-31T15:50:26","guid":{"rendered":"https:\/\/uwm.edu\/field-station\/?p=16601"},"modified":"2025-11-03T08:17:58","modified_gmt":"2025-11-03T14:17:58","slug":"dewdrop-spider","status":"publish","type":"post","link":"https:\/\/uwm.edu\/field-station\/bug-of-the-week\/dewdrop-spider\/","title":{"rendered":"Dewdrop Spider"},"content":{"rendered":"\n

Greetings, BugFans,<\/p>\n\n\n\n

In honor of Halloween, we\u2019re ending the month with a spider. A very cool little spider with a big story.<\/p>\n\n\n\n

The Dewdrop spider Argyrodes elevatus<\/em> (Argyrodes<\/em> means \u201csilver-like), in the Cobweb\/Comb-footed\/Tangle-web spider family Theridiidae, doesn\u2019t live around here, though other genera of Dewdrop spiders do, like Neospintharus trigonum – BugGuide.Net<\/a> and the awesome lizard spider Really weird spider – Rhomphaea fictilium – BugGuide.Net<\/a>. Theridiids are found in North America, indoors and out, in an almost infinite variety of habitats, from border to border and from sea to shining sea (and around the world). Thanks, as always, to BugFan Tom for sharing his pictures. <\/p>\n\n\n\n

Argyrodes<\/em>\u00a0spiders are also called Robber spiders (more about that in a sec), and there are three genus members in the US, and more elsewhere. Argyrodes elevatus<\/em>\u00a0is found in California and in much of a swath of Southern\/mid-Southern states from Texas to Ohio to Delaware, the Carolinas, and Florida. Their silvery abdomens give them their \u201cdewdrop\u201d name, and they\u2019re seriously small \u2013 females are a shade smaller than \u00bc inch, and males are smaller still.\u00a0<\/p>\n\n\n\n

Dewdrop spiders are inquilines \u2013 animals that exploit the living space of other animals (sometimes passively and sometimes impactfully). These tiny spiders can and do spin their own silk, but they prefer to live at the outskirts of larger spiders\u2019 webs. A host\u2019s web may contain a lot of them \u2013 so small that she may not even notice them. For scale, here\u2019s one in a web with another spider and a partly-wrapped, inch-long green June beetle Somebody’s pulling the golden silk spider’s chain – Argyrodes elevatus – BugGuide.Net<\/a>.<\/p>\n\n\n\n

\"Spider<\/figure>\n\n\n\n

When a male goes a\u2019courtin,\u2019 possibly attracted by a female\u2019s pheromones, he arrives bearing a gift \u2013 prey wrapped in silk \u2013 and he doesn\u2019t approach closely until she has accepted it. Giving nuptial gifts is uncommon in spiders. He also vibrates the web to identify himself, spider love being a chancy thing. A day after she mates (an act that, contrary to the brief encounters of other spiders, may take two to eight hours, during which she\u2019ll eat his gift), the female will tuck one or two egg sacs onto threads at the periphery of her host\u2019s web. Although she continues to live on the web, her egg sacs are on their own. <\/p>\n\n\n\n

The big story about Dewdrop spiders is how they get their food. They\u2019re \u201ckleptoparasites\u201d (triple word score) \u2013 animals that rob food from other animals. They eat wrapped prey that the host spider has stored in the web (and they can tackle wrapped prey that\u2019s quite a bit larger than they are if the host spider has already injected tenderizing enzymes), freshly caught prey that the host hasn\u2019t detected yet, the host spider\u2019s egg sacs, the host\u2019s protein-rich silk web (especially when prey is scarce), and sometimes, the host spider herself, if there are a large number of \u201cguests\u201d to gang up on her (Tom has observed Dewdrop spiders feeding on Gastracantha<\/em> spiders Crab Spider – Gasteracantha cancriformis – BugGuide.Net<\/a> in his yard). Theridiids aren\u2019t the only spider family that has food robbers, but they are the family with the most kleptoparasitic species.<\/p>\n\n\n\n

\"Shiny<\/figure>\n\n\n\n

They stay hidden, and they may alter parts of their host\u2019s web so they can remove prey without causing the telltale vibrations that might alert the bigger spider. They\u2019re very good at it \u2013 one study assigned them a 67% success rate – and they can liberate a bit of their host\u2019s food in as little as 12 seconds.<\/p>\n\n\n\n

To support their lifestyle, Dewdrop spidershave developed some interesting behaviors. Here are some highlights from a paper called \u201cNotes on the behavior of the kleptoparasitic spider Argyrodes Elevatus<\/em> (Yheridiidae, Araneae)\u201d by Marco Cesar Silveira and Hilton F. Japyass\u00fa (Notes on the behavior of the kleptoparasitic spider Argyrodes Elevatus (Yheridiidae, Araneae)<\/a>).<\/p>\n\n\n\n

<\/p>\n\n\n\n