⚡ CHEAT SHEET

Ch.6: Cockroaches

What the exam tests on the four common MI cockroaches, plant-associated and outdoor species, egg case ID, habitat preferences, and bait strategies.

🎯 Top 5 Traps

"Albino cockroaches" mean the population is LARGE — not dying. What clients see as "albino" are just-molted nymphs that are ivory white for several hours before darkening. Nymphs normally molt in private; if you can see them, the population is so large that nymphs can't find unoccupied harborage. Counterintuitive trap because clients (and students) read white = weak.

German has TWO STRIPES on the pronotum. Brown-banded NEVER has stripes — it has BANDS on the wings/body. Easy mass-confusion: both names contain "brown," both are about 1/2 inch, both are major indoor pests. ID rule: stripes on pronotum = German; light bands behind pronotum and across wings = brown-banded.

Oriental cockroach female is WINGLESS — only domestic species where the female lacks wings. Female has only short, triangular wing pads. Male has short broad wings leaving 1/4 of abdomen exposed. Neither sex flies. (American cockroach, by contrast, has wings on both sexes — male wings extend slightly past the abdomen, female wings don't reach the tip.)

Surinam cockroach in the United States = ALL FEMALES. Reproduces parthenogenically. The chapter is explicit: "No males are found in the United States." Hitchhiker in plant soil; primarily established in southern Florida and Texas. Important for greenhouse/interior plant facility pest management.

Woods cockroach is the ONLY species in this chapter for which NO PESTICIDE APPLICATION IS NEEDED. Once indoors, woods cockroaches soon die — human habitats lack the moisture of their woodland habitat AND males die without females. Control = exclusion only: caulking, screens, regulating outside lights that attract them.

🔢 Numbers You Must Know

Number

What It Represents

1/2 inch

Adult length of GERMAN and BROWN-BANDED cockroaches (about the same size — main domestic pest size)

1 1/3 to 1 1/2 inch

Adult length of AMERICAN cockroach — the largest common species; conspicuous markings on pronotum

1 inch / 1 1/4 inch

Adult ORIENTAL male / female (female slightly larger; female has only wing pads)

1/4 inch

German cockroach egg capsule length. 30 to 40 eggs per capsule.

1/8 inch

Brown-banded egg capsule length (smaller than 1/4 in). Glued in CLUMPS under furniture, behind drawers, in cabinets. 13-18 nymphs per case; 14 cases per female lifetime.

5/16 x 3/16 inch

American cockroach egg capsule (larger than 1/4 in). 14 eggs average per capsule; 12-24 capsules in warm months.

3/8 x 1/4 inch

Oriental cockroach egg capsule — irregular, black. 8 capsules/female, only ONE generation per year in cool winters.

4 to 8 capsules

German cockroach female lifetime egg case production. First few have full complement (30-40 eggs); later capsules may have fewer.

3 weeks

Time German female carries egg capsule (half-protruding from abdomen); drops about ONE day before hatching.

2 months

German cockroach development time from egg hatch to adult. Also egg-to-hatch time for Oriental and Surinam plus lower temps.

50 days

Brown-banded egg capsule incubation at room temp (up to 95 days at 72 degrees F)

1 in 20

Egg cases that can still hatch even if cockroach population is eliminated — drives the post-treatment "little black ones" complaint

20 to 21 months

American cockroach total life span (adults commonly live more than 1 year past 6-20 month nymphal stage)

2 sq ft

Maximum spot treatment area in non-food applications (ties back to Ch.4 Reg)

🔀 Easily Confused

Pair / Group

Distinguishing Feature

German vs Brown-banded

Both about 1/2 inch. German: TWO STRIPES on pronotum; egg cases CARRIED until day before hatching; loves kitchens with sink traps. Brown-banded: pronotum has light side margins (NO stripes); LIGHT BANDS across body and wings; egg cases GLUED in clumps; flourishes in WARM apartments; favors high cabinets and warm motors (TVs, clocks).

American vs Oriental

Both large, both called "waterbug." American: 1 1/3 to 1 1/2 in; reddish-brown; light yellow pronotum margin; both sexes WINGED; lives in warm moist places (boiler rooms, decaying trees). Oriental: 1 to 1 1/4 in; very dark brown/black; female WINGLESS; ONE generation/year; tolerates cooler temps; crawl spaces, foundations, floor drains.

Brown vs Smoky brown vs American (all Periplaneta)

American: light yellow pronotum margin; slender pointed cerci. Brown: lacks light pronotum coloration; cerci wider with blunt tips; transported in plant soil; sewers/crawl spaces. Smoky brown: dark mahogany; NO light markings on pronotum or wings; gutters, roof shingles, attics; very moisture-dependent.

Australian vs Brown vs Surinam (all plant-associated)

Australian: looks like American but with conspicuous LIGHT-YELLOW pronotum margins; introduced on tropical interior plants. Brown: transported in plant soil; sewers/crawl spaces/garages. Surinam: ALL FEMALES in US; hitchhikes in plant soil.

Woods vs Asian (outdoor)

Woods: lives in rotted logs, tree stumps, firewood; males fly to lights; ONCE INDOORS THEY DIE; no pesticide needed. Asian: looks IDENTICAL to German but lives outdoors; attracted to light (unlike most roaches); brought to MI by travelers from southern states.

Aggregation pheromone vs Sex pheromone

Aggregation pheromone: short-range odor that holds adults + larger nymphs together in harborage; facilitates mating by keeping sexes proximal. Sex pheromone: females release to attract males for mating; American cockroach sex pheromone is available commercially for traps.

What CAUSES cockroaches to leave favorable harborage

All of these: population pressure, intensive cleaning, pesticide applications, reduction of temperature/humidity. They don't leave easily — only negative changes drive migration.

🪳 Cockroach Species ID — Quick Reference

FOUR MOST COMMON IN MICHIGAN

Species

Size & Pronotum

Habitat / Key Fact

German

1/2 in; TWO black stripes on pronotum

Kitchens with moisture (sink traps, leaks). Largest # of phone calls, largest # of control failures. 30-40 eggs/case. Multi-technique required.

Brown-banded

About 1/2 in; pronotum dark with light side margins (NO stripes); light bands behind pronotum + across wings

Warm overheated apartments/offices. High cabinets; near stoves and warm motors (TVs, clocks, refrigerators). Egg cases GLUED in clumps under furniture.

American

1 1/3 to 1 1/2 in; reddish-brown; pronotum has yellow/light margin

Warm moist habitats — boiler rooms, basements, water sumps, decaying trees, woodpiles. Both sexes winged (males extend past abdomen; females don't). 20-21 month life span.

Oriental

Male 1 in / Female 1 1/4 in; very dark brown or shiny black; female WINGLESS (wing pads only)

Crawl spaces, foundations, floor drains, basements, mulch, water meters. Tolerates cooler temps. ONE generation/year. Most sensitive to lack of water.

PLANT-ASSOCIATED & OUTDOOR SPECIES

Species

Distinguishing Feature

Habitat / Mgmt Note

Australian

Like American but conspicuous light-yellow pronotum margins; oval shape

Tropical plants used inside shopping malls/buildings. Burrows into plant soil.

Brown

Like American but no light pronotum margin; cerci wide with blunt tips

Transported in plant soil — sewers, crawl spaces, garages.

Smoky brown

Slightly over 1 in; striking dark mahogany; no light markings

Greenhouses; gutters and roof shingles; attics. Very moisture-dependent.

Surinam

Female ~1 in; shiny black head/pronotum; brown wings; ALL FEMALES in US

Hitchhikes in plant soil. Treat plant soil with granules/drenches.

Woods

Slightly less than 1 in; slender (3x longer than wide); pronotum/wings margined with yellow/white

Rotted logs, tree stumps, firewood. Males fly to lights, brought in with firewood. ONCE INDOORS THEY DIE — NO PESTICIDE NEEDED.

Asian

Looks IDENTICAL to German cockroach

Outdoor populations only (under leaves, ground cover). Attracted to light (unlike most roaches). Brought to MI by travelers from south.

🥚 Egg Case & Mgmt Quick Reference

Species

Egg Case Size / # Eggs

Behavior / Q-Match

German

1/4 in; 30-40 eggs/case; 4-8 cases/lifetime

Carried 3 weeks; dropped ~1 day before hatch in secluded spot.

Brown-banded

1/8 in; 13-18 nymphs/case; 14 cases/lifetime

GLUED in clumps under furniture, behind drawers, in cabinet corners.

American

5/16 x 3/16 in; 14 eggs avg; 12-24 cases/warm season

Dropped ~1 day after forming. Clean dark cases in OPEN = high population.

Oriental

3/8 x 1/4 in irregular black

Carried just over 24 hours, then placed in protected spot. Hatch in 2 months. ONE generation/year.

Brown

Over 1/2 in; avg 24 eggs

35 days deposition to hatching; first nymphal stage has WHITE antennal segments at base AND tip.

Smoky brown

Large dark brown; avg 17 eggs (up to 24)

GLUED to objects. Hatches within 50 days. Yearly life cycle; large fall die-off.

💡 Memory Hooks

Albino = abundance: "White roach? Big infestation." Just-molted nymphs visible only when normal hiding spaces are full.

German vs brown-banded: "Stripes on the back, bands on the wings." German = pronotum stripes; brown-banded = body bands.

Oriental female: "Wing pads, not wings." The only domestic species with a wingless female.

Surinam = sisters only: "All females in the U.S." Parthenogenic in this country — plant soil hitchhiker.

Woods = waste no spray: "Caulk and lights — no pesticide." Indoor woods roaches die without moisture and females.

🃏 Drill 7A flashcards

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