Diffuse Knapweed Centaurea diffusa Lam.

Agapeta zoegana
L.

DESCRIPTION: Moth - 1 to 2 cm yellow body with black stripes
BACKGROUND LIFE CYCLE
Availability Habitat Adult Emergence Egg Laying Larva Development F1 Adult Life Span Over Winters
G Cooler areas of knapweed range Mid June to mid August Mid June to mid August In root   10 to 14 days Larvae in root crown
ATTACK COLLECTION NOTES
Stage Damage Life Stage Method Due to adults short lifespan, collection and redistribution within 2 to 3 days
Larvae -Root minerAdults July to AugustAspirator

Chaetorellia acrolophi
White & Marq.

DESCRIPTION: Fly - dark body with yellow bands on body and wings
BACKGROUND LIFE CYCLE
Availability Habitat Adult Emergence Egg Laying Larva Development F1 Adult Life Span Over Winters
N Dry south facing slopes scattered plants Early June coinciding with Diffuse knapweed budding Early June in flower buds Center of flower bud Two generations per year; generations overlap in July 17 days Larvae in seed head
ATTACK COLLECTION NOTES
Stage Damage Life Stage Method F2 possible but rare. 1st generation larvae and pupae are white, 2nd generation larvae and pupae are yellow.
Larvae -Seed head feederLarvae fall or early springClip seed head

Cyphocleonus achates
(Fahr.)

DESCRIPTION: Weevil - 0.5 to 1.75 cm mottled grey-brown
BACKGROUND LIFE CYCLE
Availability Habitat Adult Emergence Egg Laying Larva Development F1 Adult Life Span Over Winters
G Hot dry coarse textured sandy soils; large roots Mid July to early September Late July to mid Sept. in root crown Root crown   10 weeks Larvae in root crown
ATTACK COLLECTION NOTES
Stage Damage Life Stage Method During hot weather adults locate on top of plants.
Larvae -Root minerAdult July to early SeptemberHand pick
Adult -Foliage

Larinus minutus
Gyll.

DESCRIPTION: Weevil - 5 to 10 mm mottled brown
BACKGROUND LIFE CYCLE
Availability Habitat Adult Emergence Egg Laying Larva Development F1 Adult Life Span Over Winters
N Hot dry areas Early May to June June to July in flower buds In flower head Late September to October 5 to 14 weeks Adult in soil and litter near root
ATTACK COLLECTION NOTES
Stage Damage Life Stage Method Larvae consume the entire flower head contents.
Larvae -Flower head feederAdults early summerSweep net aspirate hand pick

Larinus obtusus
Gyll.

DESCRIPTION: Weevil - 8 mm dark brown
BACKGROUND LIFE CYCLE
Availability Habitat Adult Emergence Egg Laying Larva Development F1 Adult Life Span Over Winters
N Warm dry conditions Mid May End of May In flower head Mid July 5 to 6 months Adult in litter
ATTACK COLLECTION NOTES
Stage Damage Life Stage Method Occasionally adults hibernate a second time and live a second season.
Larvae -Seed head feederAdults early summerSweep net

Pelochrista medullana
(Strig.)

DESCRIPTION: Moth - 14 to 21 mm grey and mottled brown
BACKGROUND LIFE CYCLE
Availability Habitat Adult Emergence Egg Laying Larva Development F1 Adult Life Span Over Winters
N Moderately moist dense stands Mid June to end of July Mid June to mid August In root   12 to 13 days Larvae in root collar
ATTACK COLLECTION NOTES
Stage Damage Life Stage Method Larvae will only develop on rosettes.
Larvae -Root minerAdults mid June to end of JulyAspirator

Pterolonche inspersa
Strig.

DESCRIPTION: Moth - 14 to 28 mm grey-white
BACKGROUND LIFE CYCLE
Availability Habitat Adult Emergence Egg Laying Larva Development F1 Adult Life Span Over Winters
N Hot dry sites with low to moderate plant densities June to early September June to September In root   15 to 16 days Larvae in root
ATTACK COLLECTION NOTES
Stage Damage Life Stage Method P. inspersa will consume new Sphenoptera jugoslavica.
Larvae -Root minerNot yet determined 

Puccinia jaceae
Otth.

DESCRIPTION: Rust colored pustules 0.4 to 1.3 mm diameter
BACKGROUND LIFE CYCLE
Availability Habitat Adult Emergence Egg Laying Larva Development F1 Adult Life Span Over Winters
G Wherever Diffuse knapweed occurs 12 to 16 days after innoculation N/A N/A   N/A Pustules on stem and leaves
ATTACK COLLECTION NOTES
Stage Damage Life Stage Method Rust spreads by wind spread spores. Check for presence before redistributing.
Pustules -Leaves/reduce plant growth and vigorInfected plant material August to SeptemberClip infected stems and leaves

Sphenoptera jugoslavica
Obenb.

DESCRIPTION: Beetle - 7 to 10 mm elongate-oval; dark copper to black
BACKGROUND LIFE CYCLE
Availability Habitat Adult Emergence Egg Laying Larva Development F1 Adult Life Span Over Winters
G Arid environment with summer drought period July Mid July to mid August Root core   4 weeks Larvae in root
ATTACK COLLECTION NOTES
Stage Damage Life Stage Method Males emerge 1 week before females.
Larvae -Root minerAdults mid July to mid AugustSweep net

Urophora affinis
Frauenfeld

DESCRIPTION: Fly - 1 to 3 mm dark body clear wings with faint bar markings
BACKGROUND LIFE CYCLE
Availability Habitat Adult Emergence Egg Laying Larva Development F1 Adult Life Span Over Winters
G Where Diffuse knapweed is found Early to mid June Early to mid June Flower head Late August 3 weeks Larvae in seed head
ATTACK COLLECTION NOTES
Stage Damage Life Stage Method Bulk storage of stems attracts predatory mite. Does best in mesic and wetter years.
Larvae -Seed head gallLarvae early spring and fallClip seed heads
Adults June and JulySweep net

Urophora quadrifasciata
Meigan

DESCRIPTION: Fly - 1 to 3 mm black body, distinctive "UV" pattern on wings
BACKGROUND LIFE CYCLE
Availability Habitat Adult Emergence Egg Laying Larva Development F1 Adult Life Span Over Winters
G Where Diffuse knapweed is found Late June to early July Late June to early July Flower head Early to mid August 3 weeks Larvae in seed head
ATTACK COLLECTION NOTES
Stage Damage Life Stage Method Adults usually hold wings in a "V" shape when at rest. Larvae intolerant of severe winter conditions.
Larvae -Seed head gallLarvae early spring and fallClip seed heads
Adults June to JulySweep net

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