Natural Pest Enemies

Pest Stop

Sampling for predators and parasitoids is as important as monitoring pest populations. Higher pest densities can be tolerated when populations of natural enemies are also high. For example, a mite spray may be warranted in apple when there are two or three mites per leaf if there are no natural enemies, but a grower might wait until there are five or six per leaf if one predator mite per leaf is also present. Monitoring parasitoid populations can be tricky as often it is only the signs of their presence that can be readily detected. For example, aphid parasitoids that feed within their hosts cause the aphids to become puffy or mummified and tan, golden, or black in color. A round hole can be observed where the wasp has cut its way out of the aphid mummy.

Braconids

Braconids

Hosts:
Ants, aphids, armyworms, beetle’s larvae, bollworms, cabbageworms, caterpillars, codling moths, corn borers, cutworms, imported tent caterpillars, leafhoppers, leafminers, maggots, midges, plant bugs, scales, tomato hornworms, weevils, and many more.

Description:
Eggs and larvae of Bracons are found inside the hosts’ bodies. The larvae are tiny, cream-colored grubs that feed in or on other insects. Larvae molt five times and undergo 5 instars. Pupae of some species live and pupate within the host until they mature; others pupate in silken cocoons on the outside of the body of the host, while others spin silken cocoons away from the host. Adult wasps are tiny, about 2.5 mm in size, slender black or brown with threadlike waists. Female wasps lay eggs into the eggs of hosts’ pests but prefer caterpillars’ bodies. In cases where aphids are the host pests, aphids are not killed instantly. Aphids continue to feed on plants tissues until the Braconid larvae inside their bodies completely consume them. The fully-grown Braconid larvae cement the dead aphids to the leaf surface making aphids’ shells black and mummified. About a week later, the adult Bracon wasps cut round holes in the mummies and emerge. The empty mummies remain on the leaf. The presence of mummies in a colony of aphids is a sign that Bracons are present.

Conservation:
Adult Bracons feed on nectar, honeydew, or pollen before laying eggs. Dill, parsley, yarrow, zinnia, clover, alfalfa, parsley, cosmos, sunflower, and marigold are flowering crops that attract the native braconid populations and provide good habitats for them.

Damsel bugs

Damsel Bug

Hosts:
Aphids,  armyworms,   asparagus    beetle, Colorado potato beetle eggs and nymphs, corn earworm, corn borer, imported cabbageworm, leafhoppers, mites, moth eggs, sawfly larvae, and tarnished plant bug nymphs. Although they can survive for about two weeks without food, they will eat each other if no other prey is available.

Description:
Eggs are deposited in soft plant tissues where they are so difficult to find. Nymphs resemble adults and develop through 5 nymphal stages in about 50 days. Adults are tiny, about 2-4 mm long, with slender bodies and are yellowish or gray or reddish-brown in color. They have piercing-sucking mouthparts, a 4-segmented beak, elongated heads, and 4 long segmented antennae. They are fast runners with long slender back legs and enlarged forelegs for grasping prey. They are commonly found in most agricultural crops, especially legumes, throughout the year. Adults begin laying eggs soon after emergence.

Conservation:
They prefer to live in soybeans, grassy fields, and alfalfa. You can collect damsel bugs in alfalfa fields and release them around your garden.

Ground beetle

Ground Beetle

Hosts:
Slugs, snails, cutworms, cabbage root maggots, grubs and insect pupae, and small caterpillars

Description:
Eggs are normally laid singly in the soil. Larva is elongated and tapered toward the end, worm-like in appearance and have a large head directed forward. Pupa is brownish black, small and found in the soil. Adult ground beetles or Carabids are about 2-6cm long, dark shiny brown to metallic black, blue, green, purple, or multi-colored. They vary in shapes,- from elongated to heavy-bodied, – tapered head end with threadlike antennae, and have a ringed wing cover. Their heads are usually smaller than their thorax. Both adults and larvae have strong pincher-like mandibles. They have prominent long legs, which make them fast moving insects. Most species are nocturnal and they hide during the day in soil crevices, under rocks and stones, decaying logs, leaf litter, or composting materials. When disturbed or when other vertebrates prey upon them, they emit an odor or gas, as a type of defense mechanism, preventing them from being eaten by other predators. Ground beetles live on or below the ground, hence the name. Development from the egg to the adult stage takes about a year, although adults may live 2 to 3 years or longer.

Conservation:
Practice mulching in some sections of your field to provide a habitat for the ground beetles. Provide permanent beds and perennial plantings to protect population. Plant white clover and/or amaranth as ground covers.

Hoverfly

Hoverfly

Hosts:
Aphids, thrips, psyllids, scale insects, small caterpillars, and larvae of Heliotes

Description:
Eggs are tiny, about 1mm in size, ovateshaped, and glistening white. These are found laid singly and close to the developing aphid colony in the leaves, shoots, or stems of the plants. They hatch within 2-3 days. The larvae, known as Syrphids, are legless slug like maggots, about 1-13mm in length depending on their larval stages. They usually have a mottled gray, beige, or light green color. They lift their pointed heads to look for preys. Once preys are located, their mouthparts suck out the contents of the preys. Larvae are frequently found feeding on aphids in the sheltered and curled portion of leaves. They blend well with their habitat and therefore they must be looked for closely to locate them. Pupae are teardrops shaped and are found in the soil surface or in the plant’s foliage. Adult hoverflies are true flies with only two wings instead of four which most insects have. Adults are large and beautiful insects about 13 mm long. They have a dark head, a dark thorax, and a banded yellow and black abdomen. They closely resemble bees or wasps rather than flies. Their habit of hovering like humming birds gave them the names hoverflies or flower flies. They feed on pollen, nectar, and honeydew. They are good pollinators.

Conservation:
Hoverflies are attracted to all flowering plants but even more so to small-flowered herbs like wild mustard, coriander, dill, lupines, sunflower, and fennel. It is advisable to have multiple crops as adults basically feed on pollen and nectar and it is advisable to allow flowering weeds such as wild carrot and yarrow to grow between crop plants. Hoverflies’ larvae are most noticeable in the latter half of the growing season when aphids are established.

Lacewing

Lacewing

Hosts:
Aphids, leafminer, mealybugs, thrips, whitefly, armyworms, bollworms, cabbage worm, codling moths, corn borer, cutworm, DBM, fruitworm, leafhopper nymphs and eggs, potato beetle, scale insects, spider mites, and caterpillars of most pest moths. If given the chance, they can also prey on adult pests.

Description:
Eggs are found on slender stalks or on the underside of leaves. Each egg is attached to the top of a hair-like filament. Eggs are pale green in color.  Larvae are known as aphid lions. Newly hatched, they are grayish-brown in color. Upon emerging, larvae immediately look for food. They  grow to about 1 cm in length. They attack their prey by taking them with their large sucking jaws and injecting paralyzing poison, and then sucking out the body fluids of the pest. A larva can eat 200 or more pests or pest eggs a week. An older larva can consume 30-50 aphids per day. It can consume more than 400 aphids during its development. The larvae resemble alligators with pincers like jaw. However, they become cannibalistic if no other prey is available. They feed for 3 to 4 weeks and molt three times before pupation. They cover their bodies with prey debris. Pupae are cocoons with silken threads. These are found in cracks and crevices. The pupal stage lasts for approximately 5 days. Adults are green to yellowish-green with four, delicate transparent wings that have many veins and cross veins. Adults are about 18 mm long, with long hair-like antennae and red-gold eyes. Each adult female may deposit more than 100 eggs. Many species of adult lacewings do not prey on pests. They feed on nectar, pollen, and honeydew. An adult will live for about four to six weeks depending on the climatic conditions.

Conservation:
Flowering plants such as dill, cosmos, sunflower, carrots, and dandelions are good source of pollen and nectar for adults. Provide source of water during dry season.

Ladybird beetles

Ladybird Beetles

Hosts:
Aphids, mealybugs, scale insects, spider mites, whiteflies

Description:
Eggs are yellow to orange in color, football-shaped, and are laid in circular clusters of 10-50 eggs on the underside of leaves or near the aphid colony. Newly hatched larvae are gray or black and less than 4 mm long. They emerge as dark alligator-like flightless creatures with orange spots. Adult larvae can be gray, black, or blue with bright yellow or orange markings on the body. The larvae are elongate and slightly oblong in shape. They undergo four instars before pupating. The pupae are usually brightly patterned and can be found attached to the leaves and stems of plants where larvae have fed and developed. Adults are oval to hemispherical and strongly convex with short legs and antennae. Most species are brightly colored. Body length ranges from 0.8-16 mm. Their colors tell other predators that they are tasteless and toxic. When disturbed, some of them emit a strong smelling yellow liquid as a protection against other predators. Their colors vary from red, orange, steel blue, yellow-brown, or yellow elytra, frequently spotted or striped with black. They feed on pollen, nectar, water, and honeydew but aphids or other prey are necessary for egg production. They are the best-known predators of aphids and are capable of eating up to 50-60 per day and about 5000 aphids in their lifetime.

Conservation
Lady bird beetles are found in most agricultural and garden habitats. Their presence indicates that natural biological control is occurring. It is important to maintain habitats planted with several flowering crops. These give the ladybird beetles varied food sources. When food is not available, they tend to eat each other. Their beneficial predatory behavior and activities are continuous when there is no indiscriminate use of synthetic pesticides.

Rove beetles

Rove Beetle

Hosts:
Both adults and larvae are predators of root maggots’ eggs and larvae, mites, worms, nematodes, and other small insects. Adults tend to be cannibalistic, eating their own eggs and attacking other adults when food supply is low.

Description
Eggs are tiny, about 0.5 mm long and 0.4 mm wide, pear-shaped, pale green in color, and are covered with a gelatin-like material. These are laid by female adults in the soil among the roots of the root-maggot infested plants. The eggs hatch 5-10 days later. The first instar larvae are pale brown, about 1.5 mm long, slender, segmented, and tapered toward the anterior. They have large heads. The parasitic second and third instar larvae are white, have rudimentary legs, and are found within the host puparium. Before pupating, a larva will actively search for a host (pupa of maggot) in the surrounding soil. It will pupate in the pupa of the maggot by entering into its cocoon and feeding its contents, and then pupate itself inside for about 3-4 weeks before emerging as an adult. It is possible that two or more larvae enter into one maggot pupa but only one will survive and mature. Adult rove beetles are brown, reddish-brown, or black or have gray markings on the wings and abdomen, with slender elongate bodies. Their wing covers are shorter than the abdomen where most part of the abdomen is exposed. Both adults and larvae have well-developed ‘jaws’ cross in front of the head. They live mostly in decaying organic matter but are also found in moist agricultural soils or in habitats where large numbers of fly larvae live. When disturbed, they run very fast, with their abdomen lifted upward, like that of scorpions. Adults are good fliers as well.

Conservation
Provide ground covers or mulches within and around fields for rove beetles love to stay in moist decaying organic matter; provide hiding sites and alternative habitats and plant flowering borders, hedges, and other perennial habitats as a source of food and shelter; and provide protection by not spraying broad spectrum pesticides.

No related.