Insects and Related Pests in the Greenhouse Presented by Terry Ferriss, PhD University of Wisconsin—River Falls

Common Pests in the Greenhouse Aphids Thripse Fungus gnats Shore flies Whiteflies Red spider mites Cyclamen mites Leafminer Mealy bugs Scales

Aphids Description: 1/8” in size black to green in color winged and wingless “tail-pipes” “Y” shaped vein at wing tip Feeding: piercing - sucking mouth Location on plant: Found on entire plant (growing tips to roots) Primarily buds Underside of leaves Stems Signs/Symptoms: Distorted new growth / chlorosis Chlorotic pin-point spots on older leaves Honeydew and sooty mold

Honeydew and Sooty Mold Aphids & many other insects frequently excrete: Honeydew” --- shiny, sticky Ants love to eat “honeydew” Sooty mold grows vigorously on “honeydew”

Aphids (cont.) Reproduction: Female nymphs give birth to other females without mating Males and females appear outdoor as winter approaches – mate eggs overwinter 7 day life cycle possible !!!

Aphid’s Lifecycle From: Nelson, Greenhouse Mgmt book

Aphid From: Nelson, Greenhouse Mgmt book

Aphid damage to a chrysanthemum

Controlling Aphids Common crops: impatiens, dahlia, cineraria, peppers, tomatoes Management: Avoid high N fertilization wash aphids off plant Aphidied parasitic wasp Enstar (IGR) Horticultural Oil Orthene Others …..

Thrips Description: 1/32”-1/25” 2 pairs of wings dark brown / cigar shaped may be confused with a speck of dirt on sticky card Feeding: Rasping - sucking mouth Location on plant: in buds, in flowers, in leaf axils, between bulb scales Signs/symptoms: White to silver feeding scars/streaks on new growth (turn tan to brown) Distorted or malformed foliage/flowers Stunted growth Carry virus (TSWV, INSV)

Reproduction: Can complete in 2 weeks Warm or cool temps Pupates in soil

Thrips’s Lifecycle From: Nelson, Greenhouse Mgmt book

Thrips

Thrips damage

Controlling Thrips Common crops: geraniums, chrysanthemums, impatiens Management: Build resistance to chemicals quickly Sugar bait to increase exposure CO 2 = irritant and increases exposure Contact chemicals: deliver as small particle size to reach thrips hidden in leaf axils and buds. (several including Marathon, Avid) Biological control

Is it a fungus gnat or a shore fly??? Fungus gnatShort fly ResemblanceTiny mosquitoTiny fruit fly Legs/antennaeLongShort WingsClear w/ a distrinct Y shaped vein Five light spots on each gray wing Food sourcePlants, organic matter in soil, fungi algae

Fungus gnat vs. Shore fly From: Nelson, Greenhouse Mgmt book

Fungus gnats Description: 1/16”-1/8” adult looks like a tiny mosquito larvae: worm-like white with black head (1/4 “) Location : Larvae are in soil feeding on decaying OM Adults do not feed but fly around plants and lay eggs in soil Signs/symptoms: Larvae can injure roots if high populations Adults do not cause direct damage to the plant but can carry fungal spores and are very undesirable. Possible lack of vigor, chlorosis Common crops: any plant in high organic media

Fungus gnat lifecycle ( 20 – 30 days) From: Nelson, Greenhouse Mgmt book

Fungus gnat From: Nelson, Greenhouse Mgmt book

Controlling Fungus gnats Management: Avoid algae in the area Keep floors as dry as possible Clean up spilled media Eliminate weeds BT (Bacillis thurengiensis) Chemical options

Shore Fly From: Nelson, Greenhouse Mgmt book

Shore Flies Description: 1/8” dark in color, looks like tiny fruit fly Location on plant: Favor damp areas and algal growth Signs/symptoms: No direct injury to plants, but shore flies may carry plant pathogens Common crops: Found on any crop around damp areas Management: Keep algae growth down, watch fertilizer and water runoff, chemical and biological control

Shore Fly’s Lifecycle From: Nelson, Greenhouse Mgmt book

Whiteflies Description: 1/16”-1/8” wings covered with white waxy powder yellow-orange body Breed in oxalis and other weeds Life cycle of 4-5 weeks Location on plant: Underside of leaves (1 0 young lvs) fly when disturbed Feeding: Piercing-sucking mouth part Signs/symptoms: Chlorosis may leave honeydew

Whitefly’s Life cycle From: Nelson, Greenhouse Mgmt book

Whitefly From: Nelson, Greenhouse Mgmt book

Whiteflies (cont.) Sweet potato WF Poinsettia WF Sweet potato WF vs Poinsettia WF SPWF SPWF: moves slower / larger enstar / flies further / grayer PWF PWF: reproduces 30% faster Common crops: poinsettia, geranium, tomato, pepper, fuschia

Controlling Whiteflies Management: Weed control Enstar (IGR) Encarsia formosa Horticultural oil Chemical control (in nymph or adult stage) Marathon Pyrethrum others

Red Spider Mite (2 –spotted red spider mite) Description:.007”-.015” Red or orange in color Location on plant: Underside of leaves and on flowers Favorable conditions: Low relative humidity and high temperatures Signs/symptoms: Chlorotic stippling on upper leaf surface Yellow / bronzing of foliage – dry lvs If severe will see webbing cthr.hawaii.edu

Red Spider Mite Lifecycle From: Nelson, Greenhouse Mgmt book

Red spider mite Photo: NCSU gardenscure.com Photo: mumsanddahlias.com

Controlling Red Spider Mites Common crops: English ivy, marigold, foliage plants, ivy geranium Management: Wash underside of leaves Humidity / temp control Parasitic mites Biological sprays Miticides effective only on adults kenyon.edu

Cyclamen Mite Description:.007”-.015” Location on plant: Growing tips Signs/symptoms: Distorted or stunted new growth, blackened shoot tips Common crops: African violet, new guinea impatients, ivy, clematis Management: Rouge out infested plants, chemical control

Cyclamen Mite From: Nelson, Greenhouse Mgmt book

Leafminer Description: 1/16”, stout bodied flies that are black and may have a bright yellow thorax Location on plant: Leaves Favorable conditions: High nitrogen levels Signs/symptoms: Punctured leaves where females lay eggs “Mines” through leaves after eggs hatch Common crops: marigold, chrysanthemum, petunia Management: Resistant varieties, chemical/biological controls

Leafminer’s Lifecycle From: Nelson, Greenhouse Mgmt book

Leafminer

Leafminer damage From: Nelson, Greenhouse Mgmt book

Mealybug Description: 1/8”-1/4” soft-bodied insect covered in a white, waxy secretion Location on plant: Leaf axils, leaf midribs, underside of leaves Signs/symptoms: Honeydew on leaves, leaf yellowing and leaf drop, cottony white masses in leaf axils and underside of leaves, new growth is distorted

Mealybug Common crops: Foliage plants Signs / symptoms: “spitballs” in leaf axils and along veins Stunted growth Chlorosis of adjacent plant parts Feeding: Piercing-sucking mouth part Management: Rouge out infested plants, wash off plants, chemical control (nymphs are most susceptible), biological control

Mealybug Lifecycle

Mealybug From: Nelson, Greenhouse Mgmt book

Scales Description: 2-5mm soft and white to hard and dark bodied Feeding: piercing sucking mouth Location on plant: Stem, flowers, fruits, roots, crown Signs/symptoms: Silver streaking honeydew on plant, Chlorosis Common crops: woody interiorscape plants, amaranthus Management: Destroy infested plants chemical and biological controls

Scales’s Lifecycle From: Nelson, Greenhouse Mgmt book

Scales

University of Wisconsin—River Falls Thank you Terry Ferriss, PhD