Mulberry gall midge

The mulberry gall midge (Diplosis mori) is a small dipteran insect belonging to the Cecidomyiidae family. Adults are tiny, fragile-looking flies with long legs and antennae, rarely seen due to their elusive nature.

The larvae are typically spindle-shaped and yellowish-white, dwelling inside the plant tissue where they feed, often remaining undetected until the host plant shows visible damage.

The lifecycle is tightly synchronized with the growth stages of the mulberry tree. Winter is spent as diapausing larvae in the soil or under leaf litter beneath the tree canopy.

Adult females deposit their eggs into the developing buds or young foliage, where the emerging larvae induce the formation of galls, which serve as their habitat and nutritional source.

Due to the hidden nature of the larvae, identification usually relies on monitoring for the abnormal vegetative growth caused by the midge's feeding activity.

The primary host for this pest is the mulberry tree (Morus spp.), which is critical both for fruit production and as the sole food source for silkworms in sericulture.

In nurseries, infestation can be devastating, as the damage to apical buds causes stunted growth, stem deformation, and significant loss of leaf yield.

On mature trees, the midge causes leaf deformation, reducing the photosynthetic efficiency and potentially weakening the tree over multiple seasons.

The larvae secrete substances that force the plant to develop galls, which effectively divert energy and nutrients away from normal plant development.

Severe infestations can lead to premature defoliation, which hampers the tree's ability to store resources for winter survival and spring budding.

Adult emergence typically begins in early spring, concurrent with the swelling and opening of mulberry buds, providing immediate oviposition sites.

The most active period for larvae development is late spring to early summer, matching the peak period of vegetative growth in mulberry trees.

Depending on the climatic zone, the midge can undergo multiple generations per season, requiring constant vigilance from spring through late summer.

Gall formation is most noticeable during the peak of the growing season when the larvae are actively feeding within the distorted plant tissues.

As temperatures decline in autumn, the larvae migrate to the soil or crevices, entering a state of diapause to survive the winter months.

The most prominent sign of infestation is the presence of galls—abnormal swelling or wart-like growths—on leaves, stems, and buds.

• Distorted, curled, or stunted young leaves.
• Abnormal swelling of the buds, preventing normal foliage development.
• Presence of tiny larvae inside the opened galls.
• Premature leaf yellowing and dropping during the summer.

A quick field inspection involves checking for clusters of swollen buds or distorted leaf edges that feel hard to the touch.

In cases of heavy infestation, the entire shoot may stop growing, leading to a "witches' broom" appearance on the affected branches.

Sanitation is the cornerstone of management; clearing and destroying fallen leaves and debris is crucial to reducing the overwintering population.

Cultivating the soil around the base of the trees during late autumn or early spring helps expose and kill the overwintering larvae in the ground.

Systemic insecticides can be applied during the period of adult flight and egg-laying to prevent larvae from establishing inside the plant tissue.

Biological control agents, including parasitic wasps and predatory beetles, can play a significant role in naturally suppressing midge populations.

Pruning and removing heavily infested shoots early in the season can significantly prevent the spread of the pest within a plantation or nursery.