Aphids

Identification

many different species of aphids occur in the greenhouse, all varying in size and morphology; (0.5- 6.5 mm long)
colour: green to black, yellow, brown, purple, pink, grey, white
piercing-sucking mouthparts
can often be identified by the cornicles (tubes) from the end of the abdomen
sometimes present in a winged (alate) form
usually found in the wingless form (apterous)

Damage
plant sap is removed by the stylet, causing deformed leafs and shoots
excretion of honeydew, reducing photosynthesis and causing sooty mold to colonize on the leaves
often a disease vector for viruses

Beneficial Insects for control

Aphidius spp. (Hymenoptera: Braconidae)
-parasitic wasps
-lays eggs in individual aphids
Aphidoletes aphidimyza (Diptera: Cecidomyiidae)
-predatory larvae
-midge lays eggs near aphid colonies
-works well in combination with Aphidius spp.

Micromus variegatus (Neuroptera: Hemerobiidae)
-generalist predatory adults & larvae

Fungus Gnats

Identification

narrow, black fly with large wings (2.5 mm long)
long antennae
larvae are almost transparent with a black head (6 mm long)
Y-shaped venation on transparent wings

Damage
larvae feed on the young roots causing plant stunting and wilt
larvae can spread mites, nematodes, and fungi
adults can encourage pathogens such as; Pythium, Botrytis, Fusarium, Verticillium

Beneficial insects for control

Strateolaelaps scimitis (Acari: Laelapidae)
-generalist predatory mite

Atheta (Dalotia) coriaria (Coleoptera: Staphylinidae)
-generalist predatory beetle

Spider Mites

Identification

larvae are transparent and have 6 legs
adults; yellow-green to dark red, two dark spots on back
8 legs (arachnid, not insect), 0.75 mm long
bright orange-red colour when entering diapause
fine webbing on leaves in large infestations

Damage
feeding on plant tissue and sap causing yellow speckling of the leaves
distortion of young leaves and loss of chlorophyll
leaf drop and shriveling of leaves
much damage can be caused by small populations of spider mite

Beneficial Insects for control

Phytoseiulus persimilis (Acari: Phytoseiidae)
-predatory mite

Neoseiulus (=Amblyseius) fallacis (Acari: Phytoseiidae)
-predatory mite
Stethorus punctillum (Coleoptera: Coccinellidae)
-predatory be

Thrips

Identification

piercing-sucking mouthparts
larvae are tiny crawlers, pointed at both ends

adults are tiny winged insects (0.5- 1.4 mm)
fringes along both edges of wing
colour: light tan to brown to black depending on the species (some are striped on their backs
Damage
often feeding is on young leaves and flowers causing distortion in plant growth
piercing mouthparts damage leaves, fruit, and flowers leaving silvery/ grey patches on the leaves
black fecal pellets called frass is often left in the damaged area
frass can be a problem, causing sooty mold to occur

Beneficial Insects for control

Neoseiulus (=Amblyseius) cucumeris (Acari: Phytoseiidae)
-predatory mite
-primarily feed on the first larval stage of thrips

Strateolaelaps scimitis (Acari: Laelapidae)
-generalist predatory mite

Atheta (Dalotia) coriaria (Coleoptera: Staphylinidae)
-generalist predatory beetle

Whitefly

Identification

adults are winged fly-looking insects, usually found on undersides of leaves
grey to white (1.25- 2 mm long)

Damage
-plant sap is removed from the leaves and young shoots causing plant stunting and leaf drop
-excretion of honeydew, reducing photosynthesis and causing sooty mold to colonize on the leaves
-often a disease vector, ingesting virus particles when feeding and spreading them to other plants

Beneficial Insects for control

Encarsia formosa (Hymenoptera: Aphelinidae)
-parasitoid wasps
-excellent control of greenhouse whitefly
-lays eggs in pupae of Trialeurodes vaporariorum (Greenhouse whitefly)

Delphastus catalinae (Coleoptera: Coccinellidae)
-predatory beetle

Micromus variegatus (Neuroptera: Hemerobiidae)
-generalist predatory adults & larvae