Neuroptera (lacewings) is one of the ancient holometabolous insect groups, but some extant species stand as important natural enemies for biological control. As the capital city of China, Beijing has a rich fauna of Neuroptera, previously with 47 species recorded and sorted in 32 genera of seven families. In this study, DNA barcoding based on sequences of COI gene fragments is used to discriminate lacewing species from Beijing. 217 DNA barcode sequences belonging to 49 species were successfully obtained. The COI barcode data worked well for identification of almost all lacewing species herein examined except Pseudomalladaprasinus (Burmeister), in which cryptic species may exist. Twenty species of Neuroptera are newly recorded from Beijing. Besides, Nothochrysinae is first recorded from Beijing. Chrysopidiaciliata (Wesmael) and Drepanepteryxalgida (Erichson) are first recorded from China.

Male insects with large weapons such as horns and elongate mandibles would be expected to invest more on such structures than other parts of the body for advantages in male to male competition for mating. In male genitalia, however, intermediate size provides a better fit for more females than small or large sizes, and such a male would leave more offspring regardless of their body size. These predictions were tested using a static allometry analysis between body size and other trait sizes. Acanthacorydalisasiatica is a large dobsonfly (Megalotera) and males have conspicuously large mandibles used as weapons. We examined the hypothesis that the male mandibles of this sexually dimorphic species are sexually selected to enlarge, whereas the male genitalia are stable to be intermediate regardless of a great variation in body size. The results, as predicted, showed positive allometry between male body size and mandible length but negative allometry between male body size and ectoproct length (a male grasping structure). Sperm are transferred through a small spermatophore attached externally to the female genital opening, so it may be evolutionarily unnecessary to develop an enlarged male genital size. In contrast, there may be a trade-off between male mandible size and wing length, because of negative allometry between body size and wing length in males but isometry between them in females.

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Eggs of insects are immobile and must endure harsh environmental conditions (e.g., low temperatures in winter and aridity in summer) and avoid attack by egg-eating predators, egg parasites, and microbes. Females of Megaloptera lay their eggs as a single- or multi-layered egg mass, which is coated with chemical substances secreted from the female reproductive accessory glands. In this study, we observed the egg masses laid by females of two species of Sialidae (alderflies), nine species of Chauliodinae (fishflies), and 23 species of Corydalinae (dobsonflies) belonging to the order Megaloptera and examined the functions of accessory gland substances coating the laid eggs. The female accessory gland is a single tube in alderflies and fishflies but a paired pouch in dobsonflies. The amount and color of the gland substances differ greatly among species. These substances prevent egg desiccation, inhibit egg feeding by ladybird beetles, and repel ants. Most characteristics of the egg mass structures and the effectiveness of accessory gland substances reflect the phylogeny of Megaloptera, although some differ among closely related taxa.

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