Dictyna coloradensis is a small spider (9) native to Canada and the United States
(2,3). This spider, with an average adult carapace width of between 1.1 and 1.26 mm (0.04-0.05 in), tends to be slightly larger than Dictyna major spiders living in the same area(12), although these two species are still extremely difficult to distinguish between in the field (9,12). Dictyna coloradensis often builds its webs—irregularly-shaped ones (9) made in part of cribellate silk (5,12), an ancestral form of silk used by some groups of spiders, each thread of which contains hundreds or even thousands of tiny fibers and which has dry-adhesive properties (1,10)—on the branch-tips of shrubs (8), on flowering stalks of plants (9,11), and on trees (7). This spider is relatively unusual (13) because the mothers take care of their spiderlings for a time, living together in the same web and sharing with them the flies (4,7), ants8, or other prey that they catch (11,12). This behavior, which can also be seen in some other spiders in the genus Dictyna as well as in some other species, is considered a step on the path that led to the evolution of spiders with permanently social lifestyles (12,13). Dictyna coloradensis is also important for its role as a predator of insect pests (7)—a role it shares with many types of spiders (6). As this spider sometimes builds its web on agricultural fruit trees like apple and pear trees, it often captures and eats insects that are considered crop pests, such as aphids(7). However, much less beneficial plants—species such as yellow starthistle (Centaurea solstitialis) and spotted knapweed (Centaurea maculosa) that are invasive and dangerous in the western United States—provide Dictyna coloradensis, like Dictyna major, with particularly suitable habitat (9), and these spiders are correspondingly major predators of insects used to limit the spread of these weeds as well(12).
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