Insect and Mite Damage on Plants

DEPARTMENT OFPRIMARY INDUSTRY AND FISHERIES

www.nt.gov.au

Haidee Brown and Deanna ChinEntomology, Diagnostic Services

Insect and Mite Damage on Plants

www.nt.gov.auDEPARTMENT OF PRIMARY INDUSTRY AND FISHERIES

Chewing insects include caterpillars, grasshoppers, beetles and

termites. Damage is usually seen as chewed leaves and stems,

leaf mining, boring or tunnelling damage in bark, branches,

trunks and roots.

Plants may become defoliated and develop deformed or stunted

growth. If the damage is internal, the plant may show other

signs of stress or dieback. The following slides show examples

of chewing insect damage.

Chewing Insects


Larvae can chew leaves and occasionally young mango fruit. Mature larva 25 mm in length.

Large mango tip borer (Penicillaria jocosatrix)

Chewing Insects – Large mango tip borer (Penicillaria jocosatrix)


Larvae tunnel into capsicum fruit leaving holes and the fruit rots. Mature larva up to 35 mm in length.

Cluster caterpillar (Spodoptera litura)

Chewing Insects – Cluster caterpillar (Spodoptera litura)


Larvae tunnel into lily leaves causing a leaf mining effect and may also feed on the bulbs. Mature larva up to 45 mm in length.

Lily borer (Brithys crini)

Chewing Insects – Lily borer (Brithys crini)


Larvae tunnel in the leaves, producing mining trails and may cause severe distortion of foliage. Length of adult moth: 2 mm, wingspan 4 mm.

Citrus leaf miner (Phyllocnistis citrella)

Chewing Insects – Citrus leaf miner (Phyllocnistis citrella)


Larvae attack flowers, new leaf shoots and bore into the centre of canes. Holes and frass may be seen on the outside of the canes. Length of mature larva: 15 mm.

Alpinia stem borer (Conogethes pluto)

Chewing Insects – Alpinia stem borer (Conogethes pluto)


Wood moth borer Family Oecophoridae

Larvae ringbark and tunnel into stems and branches. Frass is seen on the outside of stems or branches. Trees affected include Acacia, Cassia, poinciana and raintree.

Chewing Insects – Wood moth borer Family Oecophoridae


Adults chew leaves and flowers of cucurbits leaving large holes and may kill young seedlings. Adult length: 6-7 mm.

Pumpkin beetles (Aulacophora spp.)

Chewing Insects – Pumpkin beetles (Aulacophora spp.)


Adults occur in swarms and generally attack the new leaves of a large range of native trees, ornamentals and fruit trees. Damaged leaves appear skeletonised. Adult length: About 6 mm.

Red shouldered leaf beetle (Monolepta australis)

Chewing Insects – Red shouldered leaf beetle (Monolepta australis)


Grasshoppers chew leaves of a large range of plants such as ornamentals, vegetables, fruit trees and native plants. Adult length: Varies according to species.

Grasshoppers (Family Acrididae)

Chewing Insects – Grasshoppers (Family Acrididae)


Larvae defoliate Melaleuca. Mature larvae seek pupation sites by boring into the soft bark. Length of mature larva: 2-3 cm.

Melaleuca sawfly

Chewing Insects – Melaleuca sawfly (Family Pergidae)


Egg laying causes blemishes with leaking sap on the skin of immature fruit. The flesh is unaffected but the seed is damaged. Adult length: About 10 mm.

Mango seed weevil (Sternochetus mangiferae)

Chewing Insects – Mango seed weevil (Sternochetus mangiferae)


Sting marks caused by egg laying are seen on fruit. Maggots feed on the flesh of the fruit causing decay. This fruit fly infests a wide range of fruit. Adult length: 9-10 mm.

Queensland fruit fly (Bactrocera tryoni)

Chewing Insects – Queensland fruit fly (Bactrocera tryoni)


Adults and larvae chew and bore into stems of stressed and dying trees. Adult length: 15-20 mm.

Large auger beetle (Bostrychopsis jesuita)

Chewing Insects – Large auger beetle (Bostrychopsis jesuita)


Adults ringbark stems which causes dieback of terminal shoots. Trees attacked include Acacia, Cassia, carambola, mango, raintree, native and ornamental plants. Adult length: 30 mm.

Twig girdler (Platyomopsis spp.)

Chewing Insects – Twig girdler (Platyomopsis spp.)


Termites chew and tunnel into roots, trunks and branches. Other symptoms may include ring barking, leaf drop, dying branches and mudding. Length of soldiers and workers: 10-12 mm.

Giant northern termite Mastotermes darwiniensis)

Chewing Insects –Giant northern termite Mastotermes darwiniensis)


Larvae chew the roots of grass which produces dead patches in lawn. Larva length: Varies according to species.

Cockchafer (Family Scarabaeidae)

Chewing Insects – Cockchafer (Family Scarabaeidae)


These include fruitpiercing moths, sucking bugs, thrips, scales, mealybugs,

aphids and mites. Damage symptoms include spots or lesions, scarring,

bronzing or silvering on plant tissue.

Plants may appear stunted or develop yellow or brown leaves. Sap sucking

insects such as scales, fluted scales, mealybugs, leafhoppers and aphids

excrete honeydew which promotes the growth of black sooty mould.

Sucking Insects and Mites


Thrips rasp and suck sap from leaves and fruit. Leaves may look yellow-brown, dried and burnt. Hosts include fruit trees, ornamentals and native plants. Adult length: 1-1.3 mm.

Redbanded thrips (Selenothrips rubrocinctus)

Sucking Insects and Mites – Redbanded thrips (Selenothrips rubrocinctus)


Adults and nymphs suck and rasp the flower surface causing brown scarring and discolouration. Adult length: 1-1.2 mm.

Orchid thrips (Dichromothrips corbetti)

Sucking Insects and MitesOrchid thrips (Dichromothrips corbetti)


Young leaves become crinkled from egg laying. Sucking damage is seen on flush and flowers. Leafhoppers excrete honeydew which promotes the growth of black sooty mould. Adult: 4-5mm.

Mango leafhopper (Idioscopus nitidulus)

Sucking Insects and Mites – Mango leafhopper (Idioscopus nitidulus)


Aphids suck sap from leaves, flowers and fruit. Sooty mould grows on the honeydew they produce. Hosts include fruit trees, ornamentals and native plants. Adult length: 2 mm.

Melon aphid (Aphis gossypii)

Sucking Insects and Mites –Melon aphid (Aphis gossypii)


Infests leaves stems and fruit stalks. When present in high numbers, plant vigour may be affected. Black sooty mould grows on shoots where honeydew is deposited. Adult: 3-4 mm.

Pink wax scale (Ceroplastes rubens)

Sucking Insects and MitesPink wax scale (Ceroplastes rubens)


Scales suck sap from the skin of fruit and the trunk. In large numbers, scales may kill the tree. Mature female scale: About 2 mm diameter.

Oriental scale (Aonidiella orientalis)

Sucking Insects and Mites – Oriental scale (Aonidiella orientalis)


Adults and nymphs suck sap from leaves, stems and fruit causing spots, blemishes and black sooty mould. Adult length: 3-8 mm.

Seychelles scale (Icerya seychellarum)

Sucking Insects and Mites – Seychelles scale (Icerya seychellarum)


Adults and nymphs suck sap from roots and reduce the vigour of plants. Adult length: Varies according to species.

Root mealybug (Family Pseudococcidae)

Sucking Insects and Mites – Root mealybug (Family Pseudococcidae)


Mites feed on leaves of a range of host plants causing curling, crinkling and browning of leaves. Adult length: 0.2 mm.

Broad mite (Polyphagotarsonemus latus)

Sucking Insects and Mites - Broad mite (Polyphagotarsonemus latus)


Mites feed on leaves of a range of hosts. Heavy infestations may cause leaves to turn yellow and drop off. Webbing is seen on and between leaves. Adult length: 0.4 mm.

Two-spotted mite (Tetranychus urticae)

Sucking Insects and MitesTwo-spotted mite (Tetranychus urticae)


Adults and nymphs pierce and suck sap from young shoots and small developing fruit. Feeding spots may appear as black marks or lesions. Adult length: 15 mm.

Fruit spotting bug (Amblypelta lutescens lutescens)

Sucking Insects and MitesFruit spotting bug (Amblypelta lutescens lutescens)


Adults pierce and suck juice from fruit leaving puncture marks surrounded by bruising. Adult wingspan: 100 mm.

Fruitpiercing moth (Eudocima materna)

Sucking Insects and MitesFruitpiercing moth (Eudocima materna)

Insect and Mite Damage on Plants

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