Overview
- What pests affect tea?
- Tea mosquito bug
- Shot hole borer
- Tea red spider mite
- Purple mite
- Chilli thrips
- Tea leaf roller
- Black citrus aphid
- How do I manage tea pests?
- Summary
Tea (Camellia sinensis) is a highly valuable crop and the second most widely consumed drink in the world, after water, with a global industry worth USD 9.5 billion. However, tea plants are often attacked by pests, resulting in significant crop losses. In India alone, up to 147 million kilograms of tea are lost annually. This article examines the primary pests that damage tea crops, their identification, and simple yet effective methods for managing and reducing their impact through biological approaches.
What pests affect tea?
Tea plants are attacked by a variety of pests, including mites, aphids, thrips, beetles, and moths. These pests damage various plant parts, including leaves, buds, and stems, resulting in reduced plant growth and lower crop yields.
Tea mosquito bug (Helopeltis theivora)
Adults of this species are usually 6–8 mm long and have thin bodies. Their heads are green or yellow-brown, their middle section (thorax) is dark red, and their back end (abdomen) can be black or yellow with greenish-black markings. The eggs can take up to two weeks to hatch, followed by about two more weeks for the insects to progress through their growth phases. Developmental stages include five instar stages. The total time for their life cycle can change depending on the season. The adults and instar stages damage tea plants by piercing the leaves, buds, and stems with needle-like mouthparts. They suck sap out of plants and inject toxic saliva. This causes brownish-red spots, curled leaves, and dried-up shoots.
Tea shot hole borer (Euwallacea fornicatus)
Tea shot hole borer refers to a group of closely related beetle species that are black, cylindrical, and small. Females are about twice the size of males, have wings, and grow up to 2.5 mm long. Eggs hatch within 3–6 days. The three developing stages last 2–3 weeks, followed by a pupal stage that lasts about a week. Shot hole borers damage tea plants by tunnelling into branches, blocking the plant’s vascular system, which carries nutrients. Signs of damage include borer shot holes in branches, visible tunnelling in stems, and, in severe cases, broken or fallen branches due to internal weakening.
Tea red spider mite (Oligonychus coffeae)
There are many species of red spider mite. The tea red spider mite is a tiny, red-colored pest that harms tea plants. They hatch from eggs in 4–6 days and go through three growth stages before becoming adults. Adult mites are oval-shaped, with bright red front ends and dark brown back ends. Females are larger than males, and their full life cycle can take up to two weeks, depending on the season. These mites use needle-like mouthparts to suck fluids from leaves. Damage appears as tiny white or yellow spots, along with leaf browning. They also spin fine silk webs, which can become visible if their numbers are high. In severe cases, leaves may dry up and fall off.
Purple mite (Calacarus carinatus)
The purple mite is a tiny pest that attacks tea plants and is even smaller than a red spider mite, and very hard (or impossible) to see with the naked eye. Eggs hatch in 2–3 days, and the mites go through two developmental stages before becoming adults. Their full life cycle takes 1–2 weeks, depending on the season. Adults are pink-purple and spindle-shaped, feeding on the undersides of mature leaves. Damage appears as browning or purpling of leaves, and in heavy infestations, leaves may fall off. Eggshells and shed skins can resemble dust when purple mite numbers are high.
Chilli thrips (Scirtothrips dorsalis)
Chilli thrips are tiny pests that cause serious damage to tea plants and other crops. Their eggs hatch in about a week, and they go through two nymph and pupal stages before becoming adults in around two weeks, depending on the season. Adult thrips are about 1.3 mm long, with light-yellow bodies, darker wings that may look brown, and dark stripes on their lower body. They feed on young leaves and buds. Damage appears as curled or discoulored leaves. In severe cases, leaves grow poorly and may fall off completely.
Tea leaf roller (Caloptilia theivora)
This pest is a species of moth sometimes known as the cross-leaf miner. Adult moths are dark brown in colour, featuring lighter forewings, and typically have a wingspan ranging from 10 to 14 millimetres. This insect pest causes significant damage to tea tree leaves during its larval stages. In the second instar, the larvae tunnel into leaf tissue, creating visible mines. From the third instar onward, the larvae begin curling the tips of the leaves downward, forming cone-like structures where they continue to feed and deposit frass (insect waste).
Black citrus aphid (Aphis aurantii)
This small insect, sometimes referred to as the tea aphid, has a wide global distribution and poses a significant threat to tea plants. Adult black citrus aphids are oval-shaped, measuring around 2 millimetres in length. They are usually black or dark brown, though some may appear reddish-brown. Both adults and nymphs feed by sucking sap from young leaves, which can stunt plant growth and cause leaves to become misshapen. Additionally, these aphids excrete a sugary substance called honeydew, which promotes the growth of a fungus called black sooty mould. The presence of large ant populations may also indicate aphid activity since ants often “farm” aphids in exchange for honeydew.
How do I manage tea pests?
Fortunately, there are numerous management strategies available for addressing major insect and other pest issues affecting tea, thereby reducing the damage caused by these pests in growing areas and tea gardens.
Monitoring
Look out for the symptoms mentioned above. The most common signs of pest damage to tea are discoloured leaves and the presence of holes or tunnels in the leaves. Seeing a large number of adult insect pests of one kind may mean that the developmental stages of that species may become a problem.
Cultural control
Cultural control refers to the use of specific farming or gardening methods to reduce the risk of pest infestations. The best approach will vary depending on the specific pest problem at hand. One effective method is to encourage the presence of natural predators that feed on harmful pests. Another option is to adjust shading and watering schedules. For example, keeping plants well-shaded can help reduce damage caused by thrips. Removing infested leaves or plants is another valuable approach.
Biological control
- Natural Substances: These are typically derived from plants and can be used in sprays to repel or kill pests. For instance, neem oil can be used to manage purple mites, tea red spider mites, and chilli thrips.
- Semiochemicals: These are messaging compounds that can be used to disrupt pest behaviour.
- Microbials: These are microorganisms like bacteria, fungi, and viruses that harm pests but not crops. Streptomyces lydicus is a species of bacteria that occurs naturally in soil and helps combat fungal pests.
- Macrobials: These are larger animals, like certain insects, that feed on or parasitise pests.
Chemical pesticides
Before considering the use of chemical pesticides, farmers should explore all available non-chemical control measures. These might include cultural practices like handpicking pests such as caterpillars, removing diseased plants, using resistant crop varieties, applying crop rotation and consulting the CABI BioProtection Portal for identifying and applying suitable biological control products (microbials, macrobials, natural substances and semiochemicals).
Summary
Tea crops are vulnerable to various pests, including mites, aphids, beetles, and moths, which can result in significant yield and quality losses. Identifying pest symptoms early and applying targeted control methods is key. Strategies like monitoring, cultural practices, biological control, and chemical use (where appropriate) can reduce pest impact. Emerging integrated pest management methods offer sustainable solutions for protecting tea crops.
For tailored pest management advice, visit the CABI BioProtection Portal, where you can enter your location and pest problem to explore customised solutions.
We have also prepared extensive guides on dealing with pests of specific crops, including coffee.
