Classification and Overview of Mulberry Pests

Mulberry (Morus spp.) is the sole food source for the silkworm Bombyx mori, making it the foundation of the sericulture industry. The quality and quantity of mulberry leaves directly determine silk yield – which is why pest damage on mulberry is not just an agricultural problem, but an economic one. Research published in the Asian Journal of Biological Sciences estimates average leaf yield losses from insect pest infestation at around 34.24%, translating to 4,500 kg per hectare per year. Over 300 insect and non-insect pest species are known to attack mulberry at various crop stages and seasons. To manage them effectively, it helps to first understand how they are classified and what makes each category distinct.

How mulberry pests are classified 🔗

Mulberry pests are broadly grouped into three categories based on where they feed and how they damage the plant: sap suckers, leaf eaters, and root/shoot feeders. Each group attacks the plant through a different mechanism, causes different symptoms, and demands a different management response. This classification is widely used in sericulture research and extension work because it gives farmers a practical framework for identifying and responding to infestations early.

Sap suckers: Silent damage to leaf quality 🔗

Sap-sucking pests are among the most economically damaging group in mulberry cultivation. They do not visibly consume leaf tissue, but they use specialized piercing mouthparts called stylets to penetrate the plant’s vascular tissue and drain sap directly from the phloem. Beyond the physical extraction of nutrients, many sap suckers also inject toxic or growth-disrupting substances into the plant, causing biochemical and structural changes in the leaf. The result is foliage that is unsuitable for silkworm feeding – even if it appears intact.

According to Mahadeva (2018), the major sap-sucking pests of mulberry include mealy bug, thrips, spiraling whitefly, and jassids, with mealy bug, thrips, and whitefly classified as the most damaging based on incidence data.

Mealy bug (Maconellicoccus hirsutus) 🔗

The pink mealy bug is one of the most widespread and damaging sap suckers in mulberry gardens, particularly in Karnataka, Tamil Nadu, and Andhra Pradesh. It is a soft-bodied, wax-coated insect that clusters at shoot tips, leaf nodes, and under overlapping leaf sheaths. The characteristic symptom it causes is known as “Tukra” – a bunchy-top condition where leaves become thickened, wrinkled, and crumpled. Affected shoots fail to develop normally, significantly reducing the leaf yield available for silkworm rearing. Leaf yield losses from mealy bug alone are estimated between 3,000 and 6,000 kg per hectare per year.

Jassid (Empoasca flavescens) 🔗

The jassid, also known as the leafhopper, attacks leaves from the underside, feeding along the veins. Adults and nymphs suck sap from the margins inward toward the midrib. The visible result is a distinctive yellowing and browning that starts at the leaf tip and spreads toward the center – a symptom commonly called “hopper burn.” Heavily infested leaves become dry and unsuitable for silkworm consumption. Jassid populations spike during dry, warm conditions and can spread rapidly through a garden.

Thrips (Pseudodendrothrips mori) 🔗

Thrips are minute insects that occur throughout the year but peak in summer months. Females lay bean-shaped eggs on the underside of leaves. Both nymphs and adults pierce leaf cells with their rasping mouthparts and suck out the contents, leaving behind white specks or silvery patches on the leaf surface. In severe infestations, leaves turn rusty, dry out, and fall prematurely. Thrips are also known to transmit secondary infections that further reduce leaf quality.

White fly (Aleurodicus dispersus) 🔗

The spiraling whitefly gets its name from the characteristic spiral pattern of white waxy material it deposits on leaf surfaces. Both nymphs and adults pierce leaf tissue and extract sap, causing yellowing and premature leaf drop. Prolonged dry spells followed by hot, humid weather tend to trigger whitefly outbreaks, particularly from March to June and October to December. Damaged leaves are rendered unfit for silkworm rearing due to both physical deterioration and contamination from honeydew secretions.

Leaf eaters: Direct defoliation and yield loss 🔗

Leaf-eating pests cause visible, often rapid damage by consuming leaf tissue directly. Unlike sap suckers, their impact on leaf quantity is immediate – they physically reduce the amount of foliage available for silkworm feeding. A field study conducted across mulberry gardens in Maharashtra identified leaf roller, Bihar hairy caterpillar, cutworms, and wingless grasshopper as the most frequently occurring defoliators, causing significant economic losses to sericulture farmers.

Leaf roller (Diaphania pulverulentalis) 🔗

The leaf roller caterpillar uses silk threads to roll and tie mulberry leaves together, creating a protected shelter inside which it feeds on the enclosed leaf tissue. Young larvae scrape the leaf surface, while older caterpillars consume the leaf entirely, leaving only the midrib. The rolled leaves are also contaminated and cannot be used for silkworm feeding. Infestations are especially common after pruning, when fresh, tender growth is available.

Bihar hairy caterpillar (Spilosoma obliqua) 🔗

The Bihar hairy caterpillar is a polyphagous pest – it attacks many crop plants, including mulberry – and is one of the most destructive defoliators in the sericulture belt. It occurs throughout the year, with peak infestations from August to January. Young larvae feed gregariously on the underside of leaves, scraping away the green tissue and leaving behind a mesh-like skeleton of veins. Older caterpillars become solitary and voracious, consuming entire leaves and causing rapid defoliation. Research on its biology confirms that a single female can lay between 1,000 and 2,000 eggs, making population buildup swift once conditions are favorable.

Cutworm (Spodoptera litura) 🔗

Cutworms are nocturnal caterpillars that hide in the soil during the day and emerge at night to feed. In young mulberry gardens, they cut through the base of shoots, causing the cut portion to dry and fall off – effectively destroying the growing tip of the plant. They also feed directly on leaves. Cutworms are particularly damaging in newly established plantations where plants have not yet developed woody stems, and a single night of heavy infestation can cause severe stand loss.

Wingless grasshopper (Neorthacris acuticeps nilgirensis) 🔗

As the name suggests, this grasshopper species is flightless, which limits its spread but also means infestations tend to be concentrated in specific areas. Both adults and nymphs feed on mulberry leaves, consuming large portions rapidly. Damage is most severe during the warmer months and in gardens located near uncultivated land where the pest breeds. Deep ploughing of the soil is an effective preventive measure, as it disrupts egg pods in the ground before they hatch.

Root and shoot feeders: Underground threats to plant survival 🔗

The third category of mulberry pests attacks the plant at its structural core – the roots and main stems. These pests are often harder to detect because much of the damage occurs below the soil surface or inside woody tissue. By the time visible symptoms appear above ground, the infestation is typically already severe. Root and shoot feeders like the stem borer, termites, and cockchafer beetle are considered among the most serious threats to mulberry plant survival, particularly in irrigated gardens.

Stem borer (Apriona spp.) 🔗

The stem borer is the larval stage of a longhorn beetle. The female lays eggs in bark crevices, and once hatched, the larvae bore into the stem and tunnel through the woody tissue. This feeding disrupts the plant’s vascular system, weakening the stem structurally and reducing the flow of water and nutrients to the upper parts of the plant. Visible signs include round entry holes in the stem and frass (sawdust-like excrement) deposited near the base. Severely affected branches eventually die back, and heavy infestations can kill the plant.

Termites (Odontotermes spp.) 🔗

Termites are social insects that feed on the cellulose present in plant roots and woody stem tissue. They are particularly problematic in dry, sandy soils where they establish large underground colonies. Termite attack on mulberry roots disrupts water and nutrient uptake, leading to progressive wilting and plant death. Because termites work below the soil surface and often cover their feeding galleries with soil sheaths, damage can be extensive before it becomes visible. Soil treatment with chlorpyrifos and deep ploughing are the primary control strategies used in affected gardens.

Cockchafer beetle (Holotrichia serrata) 🔗

The cockchafer beetle, also known as the May-June beetle, causes damage in its larval (white grub) stage. The grubs live in the soil and feed on mulberry roots, reducing the plant’s ability to absorb water and nutrients. Infested plants show wilting and stunted growth, and young plants in particular may die outright. Adult beetles emerge seasonally and can be attracted and trapped using light traps, which is a common integrated pest management measure used in affected areas.

Why pest classification matters for management 🔗

Understanding which category a pest belongs to shapes how it should be managed. Sap suckers that reduce leaf quality without obvious defoliation are often underestimated – but studies have shown that feeding by these pests alters the biochemical composition of leaves, including their protein, moisture, and photosynthetic pigment content. Silkworms fed on such leaves produce lower-quality cocoons with reduced silk yield. Leaf eaters, by contrast, demand more immediate mechanical or chemical intervention to prevent rapid defoliation. Root and shoot feeders require soil-level interventions – chemical drenches, light traps, and physical removal – that are entirely different from what is used for above-ground pests.

The Central Sericulture Research and Training Institute (CSRTI), Mysore, recommends an integrated approach combining mechanical removal, biological agents like Trichogramma chilonis for egg parasitism, and targeted chemical applications using DDVP with appropriate safety periods before leaf harvest. Recognizing the pest type early is what makes this integrated approach effective – applying the wrong control method wastes resources and can harm silkworm health if chemical residues remain on leaves.

What do you think? Given that sap-sucking pests can damage leaf quality without obvious visual symptoms, how might sericulture farmers identify such infestations before they affect silkworm health? And with root feeders like termites operating entirely underground, what early monitoring methods could be most practical for smallholder mulberry growers?

References

1. https://scialert.net/fulltext/?doi=ajbs.2018.41.52
2. https://www.khethari.com/blogs/news/mulberry-pests-and-diseases-identification-symptoms-and-integrated-management-practices
3. https://www.entomoljournal.com/vol1Issue4/1.1.html
4. https://www.researchgate.net/publication/379875638_Biology_of_Bihar_hairy_Caterpillar_Spilosoma_obliqua_walker_under_laboratory_conditions_on_mulberry
5. https://silks.csb.gov.in/gaya/wp-content/themes/Common_District/gaya/dpm-frame.html