Insect and Mite Damage on Plants

1. Insect and Mite Damage on Plants Haidee Brown and Deanna Chin Entomology, Diagnostic Services www.nt.gov.au

2. Chewing Insects 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.

3. Chewing Insects – Large mango tip borer (Penicillariajocosatrix) Large mango tip borer (Penicillariajocosatrix) Larvae can chew leaves and occasionally young mango fruit. Mature larva 25 mm in length.

4. Chewing Insects – Cluster caterpillar (Spodopteralitura) Cluster caterpillar (Spodopteralitura) Larvae tunnel into capsicum fruit leaving holes and the fruit rots. Mature larva up to 35 mm in length.

5. Chewing Insects – Lily borer (Brithyscrini) Lily borer (Brithyscrini) 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.

6. Chewing Insects – Citrus leaf miner (Phyllocnistiscitrella) Citrus leaf miner (Phyllocnistiscitrella) Larvae tunnel in the leaves, producing mining trails and may cause severe distortion of foliage. Length of adult moth: 2 mm, wingspan 4 mm.

7. Chewing Insects – Alpinia stem borer (Conogethespluto) Alpinia stem borer (Conogethespluto) 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.

8. Chewing Insects – Wood moth borer Family Oecophoridae 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.

9. Chewing Insects – Pumpkin beetles (Aulacophora spp.) Pumpkin beetles (Aulacophora spp.) Adults chew leaves and flowers of cucurbits leaving large holes and may kill young seedlings. Adult length: 6-7 mm.

10. Chewing Insects – Red shouldered leaf beetle (Monoleptaaustralis) Red shouldered leaf beetle (Monoleptaaustralis) 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.

11. Chewing Insects – Grasshoppers (Family Acrididae) Grasshoppers (Family Acrididae) Grasshoppers chew leaves of a large range of plants such as ornamentals, vegetables, fruit trees and native plants. Adult length: Varies according to species.

12. Chewing Insects – Melaleuca sawfly (Family Pergidae) Melaleuca sawfly Larvae defoliate Melaleuca. Mature larvae seek pupation sites by boring into the soft bark. Length of mature larva: 2-3 cm.

13. Chewing Insects – Mango seed weevil (Sternochetusmangiferae) Mango seed weevil (Sternochetusmangiferae) 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.

14. Chewing Insects – Queensland fruit fly (Bactroceratryoni) Queensland fruit fly (Bactroceratryoni) 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.

15. Chewing Insects – Large auger beetle (Bostrychopsisjesuita) Large auger beetle (Bostrychopsisjesuita) Adults and larvae chew and bore into stems of stressed and dying trees. Adult length: 15-20 mm.

16. Chewing Insects – Twig girdler (Platyomopsis spp.) Twig girdler (Platyomopsis spp.) 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.

17. Chewing Insects –Giant northern termite Mastotermesdarwiniensis) Giant northern termite Mastotermesdarwiniensis) 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.

18. Chewing Insects – Cockchafer (Family Scarabaeidae) Cockchafer (Family Scarabaeidae) Larvae chew the roots of grass which produces dead patches in lawn. Larva length: Varies according to species.

19. Sucking Insects and Mites 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.

20. Sucking Insects and Mites – Redbanded thrips (Selenothripsrubrocinctus) Redbanded thrips (Selenothripsrubrocinctus) 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.

21. Sucking Insects and MitesOrchid thrips (Dichromothripscorbetti) Orchid thrips (Dichromothripscorbetti) Adults and nymphs suck and rasp the flower surface causing brown scarring and discolouration. Adult length: 1-1.2 mm.

22. Sucking Insects and Mites – Mango leafhopper (Idioscopusnitidulus) Mango leafhopper (Idioscopusnitidulus) 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.

23. Sucking Insects and Mites –Melon aphid (Aphis gossypii) Melon aphid (Aphis gossypii) 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.

24. Sucking Insects and MitesPink wax scale (Ceroplastesrubens) Pink wax scale (Ceroplastesrubens) 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.

25. Sucking Insects and Mites – Oriental scale (Aonidiellaorientalis) Oriental scale (Aonidiellaorientalis) 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.

26. Sucking Insects and Mites – Seychelles scale (Iceryaseychellarum) Seychelles scale (Iceryaseychellarum) Adults and nymphs suck sap from leaves, stems and fruit causing spots, blemishes and black sooty mould. Adult length: 3-8 mm.

27. Sucking Insects and Mites – Root mealybug (Family Pseudococcidae) Root mealybug (Family Pseudococcidae) Adults and nymphs suck sap from roots and reduce the vigour of plants. Adult length: Varies according to species.

28. Sucking Insects and Mites - Broad mite (Polyphagotarsonemuslatus) Broad mite (Polyphagotarsonemuslatus) Mites feed on leaves of a range of host plants causing curling, crinkling and browning of leaves. Adult length: 0.2 mm.

29. Sucking Insects and MitesTwo-spotted mite (Tetranychusurticae) Two-spotted mite (Tetranychusurticae) 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.

30. Sucking Insects and MitesFruit spotting bug (Amblypeltalutescenslutescens) Fruit spotting bug (Amblypeltalutescenslutescens) 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.

31. Sucking Insects and MitesFruitpiercing moth (Eudocimamaterna) Fruitpiercing moth (Eudocimamaterna) Adults pierce and suck juice from fruit leaving puncture marks surrounded by bruising. Adult wingspan: 100 mm.