Lacewings are beneficial insects that play a crucial role in maintaining a healthy garden. They are available in two varieties, green and brown, with green lacewings being the most common. These delicate creatures help keep the population of pests, such as aphids, under control.
The lacewing life cycle has four stages: egg, larva, pupa, and adult. Overwintering occurs either as a pupa or adult, depending on the species. These insects are also often commercially available, making them easy to introduce into your garden.
Some interesting aspects of lacewings include:
- Efficient predators in their larval stage
- Adults generally emerge in the spring
- Voracious appetite for aphids and other pests
- Commonly found in yards, gardens, and forests
In summary, lacewings are beneficial insects that can be great additions to your garden ecosystem. Their strong predatory nature helps keep harmful pests in check, promoting a healthy and thriving environment for your plants.
Basic Biology of Lacewings
Green Lacewings
Green lacewings are a common type of lacewing with a transparent, delicate body and long, slender antennae. They are known for their role as beneficial insects in gardens due to their predaceous larval stage1. Some characteristics of green lacewings include:
- Bright green color
- Small heads
- Wings with a delicate, net-like pattern
- Presence of numerous species across genera2
An example of a green lacewing species is Chrysoperla carnea.
Brown Lacewings
While green lacewings are more prevalent, brown lacewings also play an essential role in biological control. Brown lacewings not only have predaceous larvae, but the adults also feed on aphids3. Some features of brown lacewings include:
- Brownish color
- Similar build to green lacewings but generally smaller
- Less common than green lacewings
An example of a brown lacewing species is Micromus tasmaniae.
North American Species
| Species | Color | Antennae | Size | Example Genus |
|---|---|---|---|---|
| Green | Bright | Long | Small | Chrysoperla |
| Brown | Brownish | Long, thin | Smaller | Micromus |
In North America, there are several species of both green and brown lacewings present across different genera. Both are prevalent across various habitats and contribute to the control of garden pests.
Anatomy of Lacewings
Lacewings are fascinating insects belonging to the order Neuroptera, and their delicate, net-like wings make them easily recognizable. They are important biological control agents, often used in agricultural pest management due to their predatory larvae. Let’s explore their anatomy in detail.
1. External Anatomy
Head
- Shape and Size: The head of a lacewing is rounded or somewhat flattened, depending on the species.
- Eyes:
- Compound Eyes: Prominent and large, providing excellent vision. They are often iridescent or metallic, enhancing their visual appeal.
- Ocelli (Simple Eyes): Some species have ocelli, used for detecting light intensity.
- Antennae: Long, slender, and filamentous. They serve as sensory organs for detecting smells and vibrations.
- Mouthparts:
- Adults have chewing-type mouthparts, suited for feeding on nectar, pollen, and occasionally other small insects.
- Larvae have specialized, sickle-shaped mandibles and maxillae, used for piercing prey and sucking out bodily fluids.
Thorax
- Divided into three segments: prothorax, mesothorax, and metathorax.
- Each segment bears a pair of legs, while the mesothorax and metathorax also support wings.
- The thorax contains powerful muscles to operate the wings and legs.
Wings
- Lacewings possess two pairs of membranous wings.
- Forewings and Hindwings: Equal in size and intricately veined, giving them a “net-like” appearance.
- Wings are usually transparent, with some species showing a slight green or brown tint.
- Wings are folded flat over the abdomen when at rest.
Legs
- Six legs, all designed for walking or gripping surfaces.
- The tarsal segments end in claws, aiding in mobility on plants and rough surfaces.
Abdomen
- Long, slender, and segmented (typically 10 visible segments).
- It houses the reproductive organs and digestive system.
- In females, the abdomen may end in an ovipositor used for laying eggs.
2. Internal Anatomy
Digestive System
- The digestive system consists of:
- Foregut: Includes the mouth, pharynx, and esophagus.
- Midgut: The primary site of digestion and nutrient absorption.
- Hindgut: Responsible for excretion.
- The diet varies:
- Adults feed on nectar, pollen, and honeydew.
- Larvae are carnivorous, preying on aphids, mites, and small arthropods.
Respiratory System
- Lacewings breathe through a system of tracheae and spiracles.
- Spiracles are openings along the sides of the thorax and abdomen, allowing air exchange.
Circulatory System
- Open circulatory system.
- Hemolymph (insect blood) circulates through the body, distributing nutrients and removing waste but not involved in oxygen transport.
Nervous System
- The central nervous system includes:
- A brain located in the head.
- A ventral nerve cord with ganglia in each body segment.
- Compound eyes and antennae are connected to sensory nerves, aiding in navigation and prey detection.
Reproductive System
- Males have testes, and females have ovaries.
- Mating involves the transfer of spermatophores.
- Eggs are laid on thin stalks, often on leaves, to protect them from predators and cannibalism.
3. Life Stages and Larval Anatomy
Lacewings undergo complete metamorphosis (holometabolism), consisting of egg, larva, pupa, and adult stages.
Larval Features
- Appearance: Resemble tiny alligators with elongated bodies and strong mandibles.
- Mandibles: Piercing and sucking, used to immobilize and consume prey.
- Prolegs: Present in some species for better mobility.
- Body: Covered with bristles or spines in some species for camouflage.
Behavioral Adaptations
- Flight: Lacewings are strong fliers, often active at dusk and night.
- Egg-Laying: Eggs are laid on stalks to prevent predation.
- Defense Mechanisms:
- Adults may release a foul-smelling chemical to deter predators.
- Larvae sometimes cover themselves with debris or prey remains as camouflage.
Importance of Lacewings
- Ecologically, lacewings play a crucial role in pest management. Their larvae, often referred to as aphid lions, are voracious predators, making lacewings beneficial in agricultural and garden ecosystems.
In summary, lacewings are not only structurally unique but also vital to maintaining ecological balance. Their intricate anatomy and life cycle highlight their role as both predators and pollinators in their habitats.
