Gnats can often be found fluttering around indoor plants. With long legs and antennae and an ultrathin body that seeps light through, they resemble mosquitoes in size while not biting like them do.
Fruit flies and drain flies alike can attract them, which they lay eggs in moist organic material like potting soil to become maggots or pupae.
Female Gnats
Gnats can be pesky insects that buzz and flit around flowers, fruits and veggies in your garden. They also swarm over houseplants, often gathering at the bottom of pots. While they may annoy with their constant buzzing and hovering, they don’t bite; in fact they resemble mini mosquitoes more than true flies with long dangling legs similar to mosquitoes; you might spot these mini mosquitoes hanging around fruit bowls, sugary snacks or trashcans searching for food sources.
Adult fungus gnats measure approximately one tenth to one eighth inch long and feature long segmented antennae that are longer than their bodies. Their eyes meet at the base of their antennae while they feature single wings with Y-shaped patterns on either side.
Fungus gnat eggs are small, creamy-white or nearly translucent ovals with shiny black head capsules that have an oval or circular notch at their tip. When laid in moist plant-derived organic debris such as leaf mold, compost piles, soil or mulch they hatch within three days provided temperatures reach 75oF or warmer.
Fungus gnat larvae appear as small maggot-like insects with shiny black heads. Their bodies range from white to clear and have lobed body segments which help them move along their journeys. Larvae are commonly found feeding on plants such as alfalfa, adolfia carnations, clover corn Easter lilies garlic kale lettuce and nasturtium roots while they may also feed from foliage like roses, cucumbers or poinsettia leaves.
Gnat larvae feed on nectar, but their presence in your garden can actually prove helpful for aeration and breaking up heavy thatch layers. Plus they consume decayed organic material and fungi found within your soil!
Fungus gnats and other pests that thrive in moist soil can be controlled by keeping it dry, reducing water usage, not letting excess sit too long, adding organic material such as compost to the soil and using fungus gnat baits to target larvae. In cases of serious infestation, professional assistance should be sought.
Eggs
Gnats undergo four developmental stages, from egg, larva, pupa and adult. Female gnats lay their eggs wherever their species thrives – from soil, water or plants – while their color varies according to species of gnat. The eggs of females gnats may also vary in color depending on where their species lives.
Eggs can be hard to see without using a magnifying glass or microscope, especially in dark soil. Gnat eggs are most frequently found in crevices or cracks of soil containing organic debris containing fungus growth; they may also be laid in moist potting mix in greenhouses, garden centers or indoor plants where their color ranges from white to yellow in hue.
At hatching time, a chick emerges from its bottom by breaking off small bits of shell with its jaws before pushing its way through with neck spasms until reaching the broad end of its egg with head tucked under right wing and facing left wing – this position allows them to push out their inner membrane and enter an air cell for its first breath; those set upside-down often die during this stage because the gnat cannot reach their head to breathe properly.
After several days of incubation, a chick turns its head towards the opening in the top of its egg and uses neck spasms to break through its internal membrane. If a chick was born with its head already tucked under its wings before birthing could not break through this membrane and would drown itself in its own excreta.
Fungus gnats are very fast reproducers, producing multiple generations annually. Adult females deposit 30 to 200 yellowish-white eggs singly or clustered on organic debris such as leaf litter, compost piles, grass clippings, root hairs and plant stems as well as in moist potting mix – often the source of damage caused by houseplant pests.
Like fruit flies, gnats tend to be most active outdoors during early morning or dusk hours. Attracted by light sources such as lamps or windowsills, they may quickly form large populations on lampposts, porches and other exposed surfaces.
Larvae
Gnats go through four distinct life stages, beginning as eggs and progressing through egg, larva, pupa and adulthood. Gnats produce many generations per year, most commonly outside in winter and spring but sometimes also indoors at any time of the year. Gnats feed and breed according to their preferred environment-be it soil, water or plants-during each of their life cycles.
Fungus gnats nest in moist organic debris of plant origin such as leaves and grass clippings, compost piles, mulch or garden soil. They may also lay their eggs in greenhouses, nurseries or potted houseplants where they become an overwhelming problem. Once their larvae hatch they feed upon decaying matter as well as roots of living plants; weakening and eventually wiping out whole plants while leaving slime trails across potting mixes surface.
Larvae of larvae have white to clear bodies with shiny black heads, are legless, and measure approximately 1/4 of an inch in length.
Gnat larvae may be seen lingering near plants or resting on the ground or flying freely at night in warmer temperatures. Their wings tend to spread more rapidly compared to mosquito larvae which possess long legs with which they move freely around. Gnats don’t possess legs at this stage like mosquitoes do and thus their wings remain relatively short and narrow.
Identification can be made easier by checking whether or not a larva has segmented thoracic legs, which are the three body segments behind its head with two pairs of legs attached each time. Larvae with segmented legs typically exhibit more streamlined body forms.
Once larvae complete their feeding cycle, they elongate and transform into pupae, leaving dark-colored marks visible on top of potting soil. Pupal stages typically last 12-14 days during which time larvae cease eating and prepare to become adults.
Emergence of adult flies may be the first indicator that there is a gnat infestation present, so be vigilant in inspecting plants, windowsills, walls and doors for signs of resting or flying gnats. Yellow sticky traps may also help capture them.
Pupae
A larva passes through five or six instars while filter-feeding on organic debris and plant roots, before progressing to pupation stage. Pupation causes body lengthening while appendages dissolve away; pupae are typically enclosed within silk cocoons. If an insect was striped during its larval stage, this pattern can still be seen on its pupal skin or chrysalis.
Gnat pupae look very much like their adult counterparts; they feature long wings and spindly legs, a mosquito-like body shape, a pair of antennae extending beyond their head, weak fliers that often rest on surfaces like media pots or run along plants and foliage.
Gnats’ life cycles depend on their environment. Fruit flies lay their eggs under fruits and vegetables in soil; drain flies form colonies near sinks; while fungus gnats may congregate near houseplants.
After hatching from their egg, gnat eggs enter larval stage. At this point, they feed until reaching fourth instar and build silk cocoon to pupate within. At this time they may secrete fluid to soften outer layers or split their skin to begin their transformation into adulthood.
Female fungus gnats lay their eggs in moist soil or plant material such as leaf mold, compost piles, mulch and grass clippings. Once laid the larvae feed for 12-14 days before transitioning into pupal stage and becoming adults; at which point all feeding stops and they complete their short seven to ten day life cycle cycle.
When hunting gnat pupae, look for oblong shapes that blend in to their environments. In some instances, they resemble butterfly chrysalises (see photo below), though in this instance it could resemble one from another insect instead. A butterfly chrysalis may be green in color or may resemble rocks or trees surface; even metallic hues might match up perfectly to its habitat color scheme! It might even feature spots or stripes from its larval skin or from being attached to its mosquito-like body.
