1. Household Arthropods: Pests & Nuisances
Useful generalizations
Identify the critter.
Is it a potential pest?
Or a scout?
Is it from an established population?
Or, did it just lose its way and end up indoors?
Understand the appropriate treatment goal:
Eradicate? Control? Manage? Tolerate?
Useful general tactics:
Periodic inspections
Remove the food source
Modify the habitat
Block access
Remove the critters
Whenever treatment is needed, verify with the PNW Insect Management Handbook.
Sometimes services from a professional pest control company may be needed.
The PNW Handbook has suggestions concerning selecting a pest control company.
*** Master Gardeners suggest research-based management. ***
MGs don’t suggest home remedies.
EPA regulations state that products used for pest control must be labeled for that purpose.
Public Health Pests
Bed bugs (Order Hemiptera: Cimex lectularius)
Increasing problem in recent years.
Hide in cracks and crevices in bedding, wallpaper, beneath baseboard, and more.
Bites may be in rows.
Client will most likely require assistance from a professional pest control company.
Mosquitoes (Order Diptera: various species)
A problem in stagnant water
Management directed at larvae
Discard standing water from containers &/or saucers, abandoned tires, and more.
Bacillus thuringiensis israelensis (Bti)
Stinging wasps (Order Hymenoptera: Yellowjackets & bald-faced hornets)
Annual colony.
The nest’s inhabitants die by mid- to late December.
The mated queens overwinter elsewhere; in spring, they begin a new colony elsewhere.
Beneficial insects; docile while foraging.
Preferred management: Avoid nesting sites until end of season.
Bumble bees (Order Hymenoptera: Bombus species)
Annual colony.
Docile while foraging.
Preferred management: Avoid nesting sites until end of season.
Jean R. Natter 2011 Household Arthropods

2. Fleas (Order Siphonaptera)
Manage fleas in sleeping areas and on the pet.
Combination of effective strategies:
Vacuum often.
Comb the pet.
Use insect growth regulator on pet.
Foggers and “bombs” are of little to no value.
Ticks (Order Acarina: Class Arachnida)
More common in drier regions of the state.
Rocky Mountain wood tick (Dermacentor andersonii); In eastern Oregon.
Black-legged tick (Ixodes pacificus)
Mainly in SW Oregon.
Less than 2% carry Lyme disease, even fewer transmit the disease.
Management:
Appropriate clothing.
Daily inspections.
To remove a tick, grasp firmly behind the head and slowly pull straight out.
Don’t coat with vaseline; don’t burn with a cigarette and/or a match.
Two potentially troublesome spiders in the PNW (Class Arachnida; Order Araneae)
Western black widow (Latrodectus hesperus):
Family Theridiidae, the cobweb spiders.
Uncommon west of Cascades.
Reclusive spider which hangs upside down in messy web in dark places.
Velvety black spider with red hourglass on undersurface of abdomen
A common widow look-a-like from the same family
False widow (Steatoda grossa)
Purple-brown color
No red mark(s)
Common in Oregon
Hobo spider (Tegenaria agrestis) is distributed throughout the PNW.
Family Agelenidae, the funnel-web spiders.
The name “aggressive house spider” is a misunderstanding of the species name “agrestis.”
Contrary to popular belief, hobo spiders don’t attack people.
Look-a-likes among the Agelenidae
a. Giant house spider (Tegenaria gigantea)
Where the giant house spider is common, it’s displacing the hobo spider.
b. Domestic house spider (T. domestica)
c. Grass spiders: (Agelenopsis species)
For further details about the hobo spider, its look-a-likes, and more
1. hobospider.org has extensive information but insufficient detail for accurate ID.
2. PLS 116: How to Identify (or Misidentify) the Hobo Spider (WSU Pest Leaflet Series)
contains the information required for accurate identification.
Fact: The only way to know if a spider bit you is to catch the spider in the act.
Fact: The brown recluse (Loxosceles reclusa) lives in the south-central US, not in the northwest.
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3. Details required to accurately ID the hobo spider and two similar species
1. Patterns on the dorsum (top surface) are
too variable to be useful.
2. Patterns on ventrum (under surface) may
be helpful or may be inconclusive:
Dots?
Look for 3 on each side of thorax.
dorsum
Or a band instead of dots?
Note: The band may be broad,
narrow, or interrupted.
3. Marks on underside of coxae (1st segment
of the legs):
Notice number of marks and their domestic house spider hobo spider giant house spider
distribution on each coxa.
Domestic: 2 marks at distal (far) end.
Hobo: Triangle on 4th coxae.
Giant: On each coxa, one mark across
distal end, 2 marks adjacent to thorax.
ventrum
4. Anatomy of male palps, or female epigyne,
is diagnostic. (See photos in PLS 116.)
(Note: Use magnification such as a
10X lens or a microscope.)
(Diagram of Tegenaria species adapted from Biology and
Medical Importance of the Aggressive House Spider,
Tegenaria agrestis, in the Pacific Northwest by R. Akre & E.
Myhre; 1991 Melanderia)
Nuisance pests
In general, nuisance arthropods don’t breed indoors nor do they damage anything indoors.
General management
Block their entry points.
Screen, seal, and caulk.
Once they’re indoors, capture and take outdoors; sweep; or vacuum.
It’s unwise to use pesticides indoors.
Useful trivia: In general, flying insects move toward light.
Box elder bugs (Order Hemiptera: Boisea rubrolineata)
During fall and winter, congregate outdoors on the warm side of light-colored houses.
Move into the wall void on coldest days, outdoors on warmer days.
Possible companions: leaf-footed bugs, bordered plant bugs, stink bugs.
Some will come indoors by following the heat gradient.
Asian lady beetles (Order Coleoptera: Harmonia axyridis)
Originally imported to SE US to manage aphids in pecan orchards.
Instead of migrating, congregate on warm side of buildings, typically 2-story and light-colored.
May come indoors; may stain surfaces when annoyed.
Can bite.
Assorted beetles from firewood (Order Coleoptera: various genera)
Various borers (long-horned borers and flatheaded borers).
Won’t infest or damage the house.
Rx: Prevention; Store firewood outdoors until needed.
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4. Spiders: (Order Arachnida: Various kinds, colors, and sizes; seldom dangerous.)
Bites, if any, are defensive.
Bites are often “dry” – that is, venom isn’t injected.
Common non-poisonous spiders in western Oregon
1. Grass spiders: Body to about 1/2 inch long, the legs banded; move rapidly.
2. Folding door spiders: Related to, and often misidentified as, trapdoor spiders.
Native to Oregon. Live in a silk-lined tube in the soil.
3. Giant house spiders: Tegenaria gigantea; originally from Europe.
Large (up to 3 inches across, including legs), move rapidly; not dangerous.
4. Cobweb spiders: Variously colored. Numerous indoors and out.
Hang upside down in messy webs.
Steatoda grossa (the “false widow”) is often misidentified as a black widow.
Household Pests
Pantry pests
Management requirements
1. Remove the food source.
2. Thoroughly clean the cupboard.
3. Store foods in rigid covered containers.
4. After cleanup is complete, pheromone traps for flour moths help trap emerging males.
Flour moths (Order Lepidoptera; several species)
Adults fly during daylight hours.
Larval food: cereals, nuts, dried fruits, and more.
a. Indian meal moth: The most common pantry moth.
Adult to 1/2-inch long, copper-colored with white “shoulders.”
First sign is often ½ inch caterpillars migrating toward ceiling.
Larvae produce silky webbing on/in foods.
b. Mediterranean flour moth
Adult is gray with darker spots; slightly smaller than the Indian meal moth.
Various beetles and weevils (Order Coleoptera: drugstore beetle; flour beetle; rice weevil; etc.)
All are very small; often 1/8 inch or less; hard-bodied; brown, gray, or black.
The drugstore beetle is most common; may be extremely numerous.
Contaminated food may have off-taste.
Ants, house-invading: (Order Hymenoptera: various genera)
Visible ants are scouts and workers; 1000s more are in the nest.
Determine where the ants are coming indoors. Then, follow the 2-way trail to locate the nest.
Rx: Place pre-formulated baits at entry points, along the 2-way trail, and at the nest entry.
Flies (Order Diptera)
Small flies
a. Fruit flies (aka vinegar flies): Small, stocky light-colored flies; large red eyes.
Rx: Trap them with juice or cider vinegar plus a drop of dish-washing liquid.
b. Dark-winged fungus gnats (Family Sciaridae) associated with plants
To 1/4”; with dark wings.
Rx: Allow surface of potting mix to dry.
c. Clear-winged fungus gnat (Family Mycetophilidae)
To 1/4”; clear wings; thorax strongly humped. Inhabits moldy places/things.
Rx: Discard moldy rags, mop, etc.
Larger flies
a. House flies: Food: carcasses & excrement. May contaminate food. Rx: Sanitation.
b. Blow flies (metallic) & flesh flies: Maggots often migrate across the floor after they leave
a carcass in the wall void. Rx: Locate and remove the “food.”
c. Cluster flies (gold hairs on thorax). Adults are a nuisance indoors during fall and winter.
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5. Fabric damagers
Most common is the varied carpet beetle, Anthrenus verbasci.
Carpet beetle (Order Coleoptera: several species.)
Varied carpet beetles are about 1/8 inch and speckled.
Larvae make small round holes in fabrics.
Foods: natural fibers, plus much more, including seeds, feathers, insect debris.
Clothes moth (Order Lepidoptera: Tineola bisselliella)
About 1/4 inch, glossy tan with a red tuft on head.
Larval damage resembles a short narrow ditch.
Adults avoid light but may fly at night.
Case-making moth (Order Lepidoptera: Tinea pellionella)
Adult 1/4 inch, front wings buff w/3 black spots each.
Larvae feeds while within an elongated case made of fibers from the damaged fabric(s).
Structural Pests
Carpenter ants (Order Hymenoptera: several Camponotus species)
Camponotus modoc is black, C. vicinus is black with red thorax and legs.
Main (primary) nest is in dead wood in landscape, pasture, etc.
Satellite (secondary) nests are in structures, typically in moist wood in walls.
Carpenter ants don’t eat wood; instead, they excavate wood for housing.
Mating flights occur during spring, often beginning in late January.
If winged ants issue from underneath the baseboard, the nest may be in the wall void.
If winged ants enter a ceiling light fixture, the nest is in the space above (ceiling void or attic).
For suspected structural infestations:
1. April through October: Look for 2-way trails outdoors from 10 PM to 2 AM.
2. Locate the main nest by following the trail.
Trim plant material to at least a foot away from the building.
Professional treatment often required.
Characteristics required to identify carpenter ants
1. Elbowed antennae
2. Slender ”waist” between thorax
and abdomen
3. Large, single petiolar node
4. Evenly rounded thoracic profile
(When wings are/were present, the
additional musculature changes the
thoracic profile.) (Source of diagram: EB0671)
More details about local ants in Identification and Habits of Key Ant Pests of Washington (EM033E)
(Download from http://www.ecy.wa.gov/programs/swfa/upest/fact_sheets/antpests.pdf)
Termites (Order Isoptera)
Dampwood termites (Zootermopsis angusticollis)
Nest in, and eat, moisture-damaged wood.
Larger and more common than subterranean termites.
Mating flights summer through fall; winged reproductives light brown.
Management may be as simple as removing and replacing the infested wood.
Western subterranean termites (Reticulitermes species)
Uncommon in our region.
Nest in the soil.
Construct protective soil tubes between the nest and the feeding site in wood.
Mating flights any time; winged reproductives black.
Management requires services of a professional pest control company.
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6. To differentiate between ants (Hymenoptera) and termites (Isoptera)
(Illustration: California Department
of Food and Agriculture)`
More info in Termites: Biology,
Prevention, and Control (EB0787)
Miscellaneous beetles (Order Coleoptera)
Golden buprestid (Buprestis aurulenta) – won’t re-infest structures
Powderpost beetles (several families) – may re-infest unprotected wood
Resources: Books
PNW Insect Management Handbook is your primary source for recommended management.
(The section titled Nuisance, Household, Public Health, Structural)
Insects (Peterson Field Guides) A helpful identification guide, with a pictorial dichotomous key to the
Orders on the inside covers.
Spiders and Their Kin (A Golden Guide)
An easily understood, well-illustrated reference for spider ID
Garden Insects (Whitney Cranshaw) Numerous images; brief bios
Is it a Spider Bite? (Page 300 in Common Sense Pest Control by Wm. Olkowski, et al.)
Discusses numerous potential causes for lesions misdiagnosed as “spider bites”
Living with Bugs (Jack DeAngelis)
The following Pest Control Technician Series (PCT) is for the professional pest control industry but
contain numerous helpful details including life cycles, foods, habitats, and cultural management.
Suggested chemical treatments may offer insights into potential professional services.
 Technician’s Handbook (R. Kramer) is a handy, easy-to-use reference
 Brief summaries, most are 2 pages, with a clear line drawing
 PCT Handbooks with in-depth information:
Structure-infesting Ants; Structure-Infesting Flies; Urban Spiders; Structure-infesting Beetles
Resources: Online
OSU Publications: http://extension.oregonstate.edu/catalog/ and at county Extension Service offices
OSU Urban Entomology: http://entomology.oregonstate.edu/urbanent/
Ken Gray Insect Image Collection, OSU: Collection of 5,000 images to help you verify an ID
http://www.ipmnet.org/kgphoto/index.cfm
Search by Keyword; use the technical name rather than the common name
Pestsense for Oregon: http://pep.wsu.edu/oregonpestsense/
http://www.ecy.wa.gov/programs/swfa/upest/fact_sheets/antpests.pdf
Identification and Habits of Key Ant Pests of Washington (EM033E)
http://www.ecy.wa.gov/programs/swfa/upest/fact_sheets/antpests.pdf
Pest Leaflet Series http://www.puyallup.wsu.edu/plantclinic/resources/pls-res.html
Informative and easy-to-understand articles written for Master Gardeners and the public
Each contains 1 to 10 pages, often with photos
Particularly useful is PLS 116 How to Identify the Hobo Spider
UC Davis Pests of Home, Structures, People and Pets
http://www.ipm.ucdavis.edu/PMG/menu.house.html
Bed Bugs (OSU) http://entomology.oregonstate.edu/sites/default/files/Bed_Bugs.pdf
Bed bug FAQ list: http://www.nysipm.cornell.edu/whats_bugging_you/bed_bugs/bedbugs_faqs.asp
Bed bugs are back! http://www.nysipm.cornell.edu/publications/bed_bugs/files/bed_bug.pdf
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