All spiders (Araneae family) develop as predators of other arthropods. Many are very common in agricultural fields and can be extremely valuable when not overly disturbed by pesticide use or cultural practices. Habits vary considerably among the different spiders with some working as active hunters that seek and physically overcome prey, some hunt by ambush, and others create webs that assist in prey capture.
Araneae: Thomisidae
Crab spiders are usually distinguished by having the front two pairs of legs being particularly elongated. Most have a fairly bulbous abdomen and all hunt primarily by ambush, waiting on leaves and flowers for prey to approach. Many have coloration that allows them to blend well with their background. In fields crab spiders can be densely populated in above-ground vegetation.
Araneae: Salticidae
The jumping spiders are some of the most active daytime hunters. They are often brightly colored and, as their name indicates, are capable of short (less than one inch) jumps. They have large eyes and excellent eyesight that allow them to track prey well. Phidippus species are particularly common in the region.
Araneae: Lycosidae
Wolf spiders are active hunters, primarily nocturnal, that do not use webbing to capture prey. They are a dominant group of spiders in agricultural fields. Activity is usually restricted to crawling on the soil surface and they rarely climb plants. Most wolf spiders are gray, brown, or nearly black and some get quite large. A curious habit is that the female carries the egg sack attached to her hind spinnerets and the newly hatched spiderlings spend a brief period carried on her back.
Araneae: Gnaphosidae
The gnapshosids are among the most common spiders that hunt the soil surface. Most are fairly uniformly brown or black, although white patterning is present on the abdomen of some species. The gnaphosids hunt at night and seek cover during the daytime. They are moderate sized, typically about 1/3 to 1/2-inch. Spiders of the genus Gnaphosa are numerous in small grains. Haplodrassus and Drassodes are other common genera in fields.
Araneae: Agelenidae
The funnel spiders, including the common ‘grass spiders’, make sheet webs with a funnel retreat in a darkened corner at the edge of the web. The webbing is not sticky and the spiders emerge to capture prey that disturb the web. The funnel weavers are gray or brown and commonly are mistaken for wolf spiders or brown recluse. Grass spiders in the genera Tegenaria and Agelenopsis are common invaders of homes in late season. They are not very common in cultivated fields but more common in grasses and areas of permanent vegetation.
Araneae: Araneaidae
The orb-web spiders include those that make the largest and most intricately patterned webs that appear among garden plants in late summer and early fall. Perhaps the best recognized are the argiope spiders which can make large concentric webs, usually have a zig-zag stripe of webbing (stabilimentum) running down the center. The banded argiope (A. trifasciata) is the largest of these spiders in the region, but many other orb-web spiders in the genus Araneus may be found in and around fields.
Aranae: Tetragnathidae
Orb-webs can also be made by the tetragnathid spiders. Some of the more common are known as long-jawed orb-weavers (Tetragnatha spp.). These possess very large jaws and have long legs that extend forward and back as they rest on plant stems. They are particularly common in more humid sites, often near water.
Araneae: Linyphiidae
Spiders of the Linyphiidae are often the common spiders found among dense vegetation such as small grains. They are small spiders, rarely exceeding 1/4-inch when full grown. Most make small webs between plants and capture prey by use of sticky threads. Their abdomen is more elongated than the cobweb and orb-web spiders, other groups that commonly make webs among vegetation. Many of the Linyphiidae have patterns of light and dark markings on the abdomen.
Araneae: Theridiidae
These spiders possess a row of bristles on the 4th pair of legs that are used to pull silk over their spinnerets. They build cobsebs or irregular tangle webs to capture prey. The widow spiders (Latrodectus spp.) are the best known of the combfooted spiders, and can be common in areas of dense vegetation. However, there are many other non-poisonous species of comb-footed spiders in agricultural fields, notably the large black Steatoda species.
Categories: Biological Control, Insects, Spiders, Crab Spiders, Jumping Spiders, Wolf Spiders, Gnaphosids, Funnel Spiders, Orb-web Spiders, Tetragnathids ,Dwarf Spiders, Sheetweb Spiders, Comb-footed Spiders
Date: 05/11/2004
