Abstract: Gall-inducing insects are a category of insects capable of causing abnormal proliferation in parasitized plants, leading to the formation of galls. There are approximately 20 families of gall-inducing insects of six orders worldwide. These insects exhibit a high degree of specificity in their parasitism but can harm multiple parts of their hosts. The most extensively affected and severely damaged part is the plant leaf, and this damage has caused significant economic losses worldwide and disrupted regional ecological balance and the stability of the biological chain. In this article, with six categories of leaf gall-inducing insects, including Cecidomyiidae (gall midges), Cynipidae (gall wasps), Eulophidae (parasitic wasps), Psylloidea (sucking lice), Aphidoidea (aphids) and Eriophyoidea (gall mites) as the focuses, the simple and complex structure of plant leaf galls was summarized. The diversity of gall morphologies on leaves was discussed around three major hypotheses, providing a deeper understanding of the significance of gall structure to leaf gall-inducing insects. The gall midge Dasineura jujubifolia was used as a case study to explore the damage characteristics of leaf gall-inducing insects and to discuss the causes of their damage from a practical perspective. The discussion integrated both existing and potential control measures for leaf gall-inducing insects, both domestically and internationally, including chemical control, agricultural control and biological control as the three major strategies. The six types of gall-inducing insects have distinctive characteristics in terms of their damaging methods, gall formation features, and the completion modes of their life cycles. The different structural composition and hormonal changes of galls correspond to explanations of the nutrition hypothesis, microenvironment hypothesis and natural enemy hypothesis. Based on the current limited research, the formation process of galls is divided into the initial stage, growth stage, maturity stage and emergence stage. A comprehensive discussion was presented on how leaf gall insects can cause changes in multiple factors such as sugars, proteins, lipids and growth hormones in the host plant by secreting specific molecules. The three major characteristics of the damage by leaf gall-inducing insects are its prolonged duration, severe degree and high difficulty in control. The control methods mainly based on chemical control before the emergence stage of adult insects, supplemented by agricultural measures during the forestry period were introduced. At the same time, biological control with natural enemies and biological agents has a broad prospect for development. Research on leaf gall insects in our country still has significant room for development. Their unique way of causing damage suggests a certain trend in the co-evolution between species, which holds substantial economic value and practical significance from both macroscopic and microscopic perspectives.

Key words: Leaf gall-inducing insects, insect galls, biological characteristics, insect-plant interactions, control strategies