Family Stratiomyidae: Soldier Fly - Actina viridis
Family Dictynidae: Mesh-Web Weaver Spider - Dictyna sp.
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The type genus of the family, Dictyna is of world-wide distribution.
Dictynid Spider & soldier fly prey
Flies in the family Stratiomyidae are commonly called soldier flies (after Greek stratiotes, soldier, refering to the abdominal markings resembling military uniform hash marks). Stratiomyids range worldwide on every continent, save Antarctica, in 400 genera containing ~1500 species [1].

Ranging from 3 to 28mm long, adults are almost always found on flowers, where they use their jointed proboscis to suck nectar to fuel their amorous activities. Wings are held scissors-like over the back while at rest, and are transparent (hyaline), darkened, with a blackish tinge (infuscate), or with a distinct pattern [2].

Antennae are highly variable in shape, with scape and pedicel short, flagellum with 5-6 flagellomeres (this species has 5), sometimes with an apical or arista-like stylus [1][2].

Soldier fly larvae are almost all aquatic, feeding on decaying organic matter. Some larvae of terrestrial species feed on dung, rotten fruit, and decomposing plant material. Other stratiomyid species have carnivorous larvae [1].

Spiders in the family Dictynidae are small, sedentary (that is, they build a web and stay in one place) arachnids that build irregular mesh webs to snare prey, and as shelters for themselves. The spider begins by spinning a simple framework of parallel rows, then overlapping those with another set at right angles. The whole web is infused with sticky ribbons consisting of dry support lines and a woof of curled threads the spider pulls from the cribellum by means of a comb of bristles, called a calamistrum, on its fourth metatarsus. [2]

Being quite gregarious spiders in habit, these webs can become a serious problem when spiders congregate in large colonies - they are known to completely blanket small trees or shrubs. In the American Southwest, these communal webs can cover the walls of buildings!

Not much is known of the life cycle of these tiny spiders, but it is thought most species live only a single year. The females produce a few eggs at a time, encasing them in small egg sacs suspended in the mesh web.

Dictynid Spider & soldier fly prey
Family Dictynidae: "Small cribellate spiders of the suborder Araneomorphae with one pair of book lungs and a single transverse tracheal spiracle immediately in front of the spinnerets. Cribellum undivided except in a few species of Mallos. Calamistrum always uniseriate and runing nearly the full length of the laterally compressed fourth metatarsus. Chelicerae robust, free at the base, with a conspicuous lateral condyle sometimes developed to a horn, and with both margins of the furrow toothed.

Legs of moderate length, only rarely with well-developed spines, and with three tarsal claws. Trichobothria present on metatarsi and tarsi except in Dictyna and some Mallos. Anal tubercle of moderate size, short, lacking a conspicuous fringe of hair. Eyes typically eight in two essentially straight rows, but the anterior median sometimes reduced in size or completely missing. [2]

References
  1. Bugguide.net, Actina viridis
  2.  RALPH V. CHAMBERLIN, WILLIS J. GERTSCH, "Family Dictynidae in America North of Mexico", Bulletin of the American Museum of Natural History Volume 116, article 1 (pdf) NOTE! Large file!
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Flies of North America - Order Diptera. Flies are prevalent in virtually all habitats, with over 16,000 species in North America. Flies are different from from all other insects in that they only have one pair of normal wings.  Most flies have compound eyes and mouthparts adapted for piercing, lapping or sucking fluids.
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Class Arachnida / Order Araneae: Spiders are the largest group of arachnids.  They are easily recognized by their eight legs, and there are few creatures great or small that elicit such irrational fear in mankind. The vast majority of spiders are completely harmless and offer beneficial services, chief of which is keeping the burgeoning insect population in check. Spiders Index | Orb Weavers | Jumping Spiders
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