Funnel weavers and grass spiders rank among the most frequently encountered spiders in and around structures. Adults of the
common peridomestic species have body lengths of 0.5 to 0.8 inches and leg spans ranging from U.S. half-dollar size to larger
than silver-dollar size.
These brown and tan spiders often are confused with wolf spiders (Family Lycosidae) because of their similar coloration and the presence of short, dense "fuzz" (setae) covering their bodies and legs. However,
funnel weavers may be distinguished from wolf spiders by the presence of:
- Paired elongate, filament-like spinnerets at the tip of their abdomens.
- A small oval or D-shaped pattern of eight tiny eyes on the front of the carapace/cephalothorax.
- Funnel weavers spend most of their time hiding in the narrow end of funnel-shaped webs (see photo below) that spread out —
across grass, dense foliage of around cover and shrubs, in the corners of window wells and foundation walls, and where siding
overlaps underlying structural elements — to esnare their prey.
In addition, funnel weaver spiders and their occassional bites are commonly mistaken for brown recluse spiders (Family Sicariidae) by both the public and inadequately trained health care professionals. The brown recluse and its relatives have only six
small eyes arranged in three groups of two (diads) at the front of the carapace. SPECIES AND BIOLOGY
Of the roughly 300 species of funnel weaver spiders found in North America, there are several that frequent buildings and
developed properties. The primary species encountered by the public and pest management professionals (PMPs) are:
- Grass spiders, Agelenopsis spp., including A. pennsylvanica.
- European house spiders, Tegenaria domestica and T. saeva.
- Hobo spiders (aka aggressive house spiders),T. agrestis, which are found mainly in the Pacific Northwest.
As with other spiders, males can be distinguished from females by the enlarged (boxing glove-like) tips of the pedipalps (used
to transfer sperm to females' epigynum, located on the underside of their abdomens). Males also have consistently slender
abdomens.
Mated female funnel spiders deposit disc-shaped egg sacs in crevices and die (if exposed outdoors). Spiderlings emerge from
the egg sacs in the spring and disperse to favorable sites in which to build their characteristic webs.
Several instars (growth stages) are passed through successive molts. In mid-summer, adult males wander to locate females with
which to mate.
Adult spiders may enter structures summer through autumn and, indoors, may extend their life expectancies into winter. Funnel
weaver spider venom is considered to be a comparatively mild cytotoxin. Complications from envenomation usually result from
bite victims having compromised immune systems, pre-existing medical conditions or contamination of the wounds by methicillin-resistant
Staphylococcus aureus (MRSA).
IPM MEASURES- Accurate spider identification requires the availability of specimens for examination. Use a practical field guide or other
illustrated reference to enable the correct identification of the spiders encountered in your service areas.
- Request that customers cut back tall and dense vegetation growing along building foundations to reduce favorable harborage
close to structures.
- Use a pest vacuum cleaner or extension-handle dusting tool to remove spider webs from structural surfaces before applying
appropriate residual liquid insecticides, or in lieu of applying insecticides in sensitive situations.
- Place sticky monitors along baseboards and floor edges along walls in structures. This will reduce spider populations indoors
and will serve as an indicator of which species are present.
- Ask customers to replace white incandescent lamps in outdoor porch light fixtures with amber-colored lamps, and mercury vapor
lamps with high-pressure sodium-vapor lamps in building security light fixtures. This will help to avoid attracting night-flying
insects, which serve as food for spiders.
Wegner is the technical director and staff entomologist of Varment Guard Environmental Services in Columbus, Ohio. You can
reach him at 614-794-8169 or e-mail gerry.wegner@varmentguard.com
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Posted 2008-09-30 18:22:48.0
