Bug of the Month Brown Lacewing / Micromus Variegatus
Cold Weather No Problem
Typically, brown lacewings become active earlier in the season than green lacewings, and are actively hunting at 4 degrees, which is much colder than most bio’s. Brown Lace wings becomes active outdoors as early as March in Wisconsin (Throne, 1971) or April in Quebec (Garland 1981b). Active adults have even been observed in December and February in British Columbia (Klimaszewski and Kevan 1985). In early spring, the adults mate and eggs are deposited about two weeks later. The adult females and the eggs are extremely cold-tolerant (Garland 1981b).
Life Cycle of the Brown Lacewing
Life Cycle of the Brown Lacewing
There are four stages to the life cycle of brown lacewing, these are: eggs, larvae, pupae and adults. A brief description of each of the stages of the life cycle is provided below.
Eggs: The adult lacewing lays its’ eggs low in the plant, providing excellent low-level control, which is rare. Females lay non-stalked eggs, usually singly or in small groups. Eggs are elongate-oval and about 1 mm or less in length. They are commonly gray, pink, or whitish and have a finely pitted surface. Eggs can occur openly in colonies of prey, but also around buds, in crevices and pits of bark, or on twig crotches or tips where they are easily overlooked.
Larvae: The hatching larvae begin to feed right away Larvae are small, slender, and have large sickle-shaped mouthparts with which to puncture prey. Larvae are tapered at the tail and have distinct legs. They are 1/3 inch (8 mm) or less in length and resemble tiny alligators. Coloration on top is commonly cream, gray, or whitish with two, lengthwise, brown or reddish stripes or rows of spots. They have prominent, paired, tubelike mouthparts that curve inwards towards the tip.
Larvae undergo three growth stages (instars), with the first one being the most active. Brown lacewing larvae prey on the same soft-bodied insects as the adults but consume aphids at a higher rate. Lacewing larvae are voracious predators and feed on aphids, phytophagous mites, caterpillar eggs and even other lacewings if there are no thoer food sources.
Often confused with Ladybug larvae, but their sickle shaped mandibles and their colouring can distinguish them from Ladybug larvae.
Brown lacewing larvae Ladybug larvae
Life Cycle of the Brown Lacewing cont.
Pupae: Pupation occurs in a loosely woven, oblong or spherical, silken cocoon. The insect’s body is partly visible through the pale fibers.
Adult : Adults are soft-bodied and have two pairs of semi-translucent, net-like wings with heavy venation that fold over the body like a tent when at rest. Adults have long, slender antennae, large, bulbous eyes and chewing mouthparts. The body and wings are commonly dark to light brown. Once temperatures warm up in early spring, brown lacewing adults will begin to emerge and will live for several months. During this time, they will mate, lay several hundred eggs, and consume soft-bodied insects (i.e., aphids, mites, mealybugs, caterpillars)
Brown lacewings are considered important biocontrol agents and, therefore, do not need to be managed in your growing area allow them to do their stuff. Some species are even bred commercially and used in greenhouses, gardens and other spaces to control pests. However, even with proper habitat and food availability, many beneficial insects are struggling due to the use of insecticides. Before using any type of chemical, read the label and only use them as the absolute last resort.
Adult Brown Lacewing Feeding
Brown Lacewing Larvae Feeding
Promoting lacewings in Gardens and Farms
- To support lacewings in your outdoor space, think about what each life stage needs. This means there needs to be a variety of flowering plants available for them to complete their lifecycle.
- Have consistently flowering plants in your space.
- Limit pesticide applications. Many insecticides are not selective, meaning they will kill both pests, beneficial insects, and other insects.
- Provide overwintering habitats by leaving some plant debris and dead leaves on the ground over the winter
