INTRODUCTION
The common name comes from their jumping ability and habit which they use to
capture prey. They are an occasional nuisance pest indoors, and some black colored species
may cause concern when people mistaken them for black widow spiders, Latrodectus spp.
About 300 species are found in the United States and Canada.
RECOGNITION
Adult body length about 1/8-3/4" (4-18 mm); robust, compact with
relatively short legs. With 8 eyes in 3 rows, front row of 4 eyes with middle pair very large,
3rd row of 2 moderately large eyes at about midlength of cephalothorax, and middle row of
2 small eyes about midway between lst and 3rd rows. Color usually black, sometimes
brown, tan, or gray, and usually with pale markings of white, gray, yellow, red,
blue and/or green; typically densely covered with hairs or scales, these often brightly
colored or iridescent. Front legs usually thicker and somewhat longer than other legs;
tarsi with 2 serrate (toothed) claws each. No snare webs, quick to jump, with
jumping power generally supplied by the 4th pair of legs.
Note that there are 3 genera with species which mimic ants, having cephalothorax
slightly pinched in at middle to resemble head and thorax and front legs held up and bent
like elbowed antennae; these species do not jump.
SIMILAR GROUPS
Crab (Thomisidae) and giant crab (Sparassidae) spiders have body usually
flattened with legs positioned/held at right angle to sides giving a crablike appearance
and many species with horns or ornaments on cephalothorax and/or abdomen.
REPRESENTATIVE SPECIES
- Phidippus audax (Hentz). Adult female body length about 5/16-5/8" (8-15 mm),
male about 1/4-1/2" (6-13 mm); color blackish with basal white band and paired white
(sometimes yellow or orange) spots on abdomen, largest spot (=fused 2nd pair) triangular,
in center, and pointing towards front, sometimes cephalothorax with white lateral bands
extending back from rear eyes and abdomen with lateral white bands and tan pattern; male
(with swollen terminal segments of palps) with large blunt cusp/knob on front of each
chalicera near fang; found throughout the United States and southern Canada.
- Zebra spider, Saiticus scenicus (Clerck). Adult female body length about
3/16-1/4" (4.3-6.4 mm), male 1/8-1/4" (4-5.5 mm); color gray (often with brown
to reddish scales intermixed) with white markings on cephalothoracic front (with
iridescent scales), behind rear pair of eyes, and laterally, and on abdomen as basal band,
middle band interrupted at midline, and rear band usually interrupted at midline, legs
white or brown with gray rings; male with chelicerae elongate, extending almost
horizontally forward, and fangs long and sinuate; found throughout northern United States
and southern Canada.
BIOLOGY
Jumping spiders do not construct snare webs but do build web retreats which are
loosely woven, saclike, composed of several envelopes, and usually have 2 openings. These
retreats are used for molting, hibernation, night-time seclusion, and egg laying; often a
different retreat is built for each function/activity. The egg sacs are typically
lens-shaped and suspended like a hammock from the retreat's walls. There is usually only I
egg sac, but occasionally there may be several present at one time.
In the New England states, Phidippus audax females lay their eggs in June and
July. The egg sac is about 3/8" (9 mm) in diameter and about 1/8" (3.5 mm)
thick. Each egg sac contains 67-166 orange eggs. The older spiderlings overwinter in the
retreat anc become adults in late April to early May. Adults are present through August.
In the New England states, the zebra spiders mate in May and eggs are laid in June and
July. Each egg sac contains 15-25 white eggs. Presumably, the older spiderlings overwinter
in the retreat and become adults in spring. Adult males are found April to July and
females from mid-May to late October.
HABITS
Unlike most spiders, jumping spiders are active during the daytime and seem tc
like sunshine. They are hunters and have the keenest vision of all spiders, being able to
detect and react to movement up to 18" (45 cm) distant; however, their night vision
is very poor. They can rapidly move both sideways and backward for short distances. They
are excellent jumpers. They either jump on passing prey, or once they locate prey it is
stalked and then pounced upon. When hunting they may jump 1 " or more (25+ mm) bui
when threatened, they may jump 20 times their body length. They employ silk as a dragline
when they jump; the dragline is anchored before they jump and acts as a safety line.
Retreats may be built under furniture, in drapery folds, between books on book shelves, in
cracks such as found in wood floors, around door and window molding, etc, Outside, they
can frequently be found under loose bark, between leaves, etc.
Indoors, they will usually be found hunting around windows and doors because more
insects are attracted to these areas. Also, their vision is best in sunlit areas.
Outdoors, jumping spiders are commonly seen running over tree
bark, under stones anc boards, on bushes, fences, decks, and the outside of buildings,
etc. They like sunny areas.
