Many pest insects are also susceptible to entomopathogens which are simply disease-causing organisms such as bacteria, viruses, protozoans or fungi.
Another example of an assassin bug is the wheel bug. It gets its name from the semicircular crest on the thorax that resembles a cog wheel. It can also inflict a painful bite.
Ambush bugs are closely related to assassin bugs and are 1/4 to 1/2 inch long. Their front legs are very thickened for grasping their prey. They wait on flowers where they are camouflaged by their matching body color. They feed primarily on wasps and flies.
Lacewing eggs are deposited at the end of long hair-like stalks which are attached to the leaf. The female lacewing deposits a small amount of stalk fluid to the leaf and the abdomen is uplifted, resulting in a viscous upright thread. An egg is deposited at the end of the thread. The thread hardens rapidly, forming a delicate stalk. This prevents the larvae from cannibalizing each other.
Lacewing larvae are elongate and have large sickle-shaped mandibles. They are active, but sluggish and soft-bodied, with tubercles (raised bumps) and long setae (hair). They are commonly called aphid lions and feed on aphids, other small insects and eggs. Some species of lacewing larvae cover themselves with the skins of their victims and other debris, thus earning the name trash bugs.
Brown lacewings resemble the green species but are brownish and are less common. There are 58 North American species. The eggs are laid on plants, but not stalked. The brown lacewing larvae differ from green lacewing larvae in that they do not possess tubercles. Both adults and larvae prey on aphids, other soft-bodied insects and mites.
Both the adults and larvae of lady beetles are predaceous on aphids, immature scale insects, mealybugs, mites and other soft-bodied insect pests as well as insect eggs. Adult lady beetles are oval shaped and most are orange or reddish with black markings. Most lady beetles are about 1/4 inch long, but many range from 1/16 to 1/2 inch. The head is concealed from above by the expanded thorax.
The convergent lady beetle is one of our most common lady beetles. Bloodred lady beetles have no black spots on their wing covers. The sevenspotted lady beetle is another common species. The twicestabbed lady beetle is black with two red spots on the wing covers.
Many lady beetle larvae are elongate, somewhat flattened and covered with small spines. They are usually dark or black with bright colored spots or bands. The legs are long and slender. Other larva are similar in shape but much darker in color. Still other larvae are cream colored and lack any markings. Some lady beetle larvae are covered with a white flocculent secretion and resemble mealybugs. Both adults and larvae are frequently found feeding among aphid populations.
Studies have found that 200-500 aphids are consumed during the larval stage, depending on the species. The adults are usually even more voracious.
Lady beetles usually pupate on the leaves of plants, suspending themselves by the tip of the abdomen by means of a sticky secretion.
As a general rule, beneficial species of stink bugs can be identified by spines projecting from the corners of their thorax, whereas plant feeders have rounded "shoulders". The predaceous species have short, stout beaks while plant feeders have long, thin mouthparts. Predaceous types feed on many insects, but especially caterpillars.
Many syrphid fly larvae are predaceous, especially on aphids. The larvae are slug or maggot-like, have no legs or visible head and are a greenish, or light translucent color.
Damsel bugs are small insects 1/8 to 3/8 inch long, yellowish to brownish in color with prominent eyes. They are important predators, feeding on a wide variety of insects including aphids and caterpillars.
Minute pirate bugs are about 1/8 inch long and black with white markings. There are about 70 North American species, and they are predaceous on many small insects and eggs. One species is an important predator on the eggs and larvae of the corn earworm.
Some mites, especially phytoseids, are predaceous upon spider mites, small insects and eggs. They are large, active mites, orange to brown in color and about 1/25 inch in length. In Europe, and to some extent in this country, the mites are reared and released in greenhouses to reduce plant feeding mite populations.
Some wasp larvae feed and pupate inside the host (endoparasites) and the emerging wasp leaves a small circular hole in the body of the host as evidence of parasitism. Many harmful insects such as aphids, whiteflies, scales, leafminers and caterpillars are parasitized. The emergence holes on aphids and scales are very obvious.
Other parasite larvae live on the outside of its host and are known as ectoparasites. Ectoparasites construct numerous small cocoons outside the body of the host. However, some endoparasites also emerge to the outside of the host and spin cocoons on the surface of the host's body when it is time for them to pupate. This is common on caterpillars. The parasite may form numerous cocoons which appear as a cottony-looking mass on the host.
Ichneumonid wasps are one of the largest families of insects with more than 3,300 species in North America. The adults vary widely in size, form and coloration. The ovipositor is usually very long, often longer than the body. The larvae are important parasites on a wide range of harmful insects.
Tachinid flies are parasitic in the larval stage and are a valuable asset in keeping many of our serious pests in check. There are about 1,300 North American species. The feather legged fly is an example of this group. Many tachinids resemble the common house fly, but are a little larger. Others are bee-like or wasp-like in appearance.
Most tachinids deposit an egg directly on the body of their host and it is not uncommon to find caterpillars with several eggs on them. Upon hatching, the tachinid larva burrows into the host and feeds internally. When developed, it leaves the host and pupates nearby.
Some tachinids lay their eggs on southern green stink bugs. Other tachinids lay their eggs on foliage and the eggs hatch inside the caterpillar after it consumes the foliage.
Velvetbean caterpillars are also infected with entomophagus fungi. The infected caterpillar's body becomes very hard, brittle and covered with the white powdery-looking spores of the fungus. As the dead caterpillar ages, the color may become light green. The disease is prevalent in late summer and early fall months. Once the disease appears, it can quickly infect an entire population of caterpillars.
Aphids can also become infected with a fungus. The infected body generally becomes tan or pink in color. As the disease progresses, the body becomes flattened and appears to increase in size as the mycelium expands from the aphid. When weather conditions are favorable, the fungus will drastically reduce aphid populations in a short time.
Immature stages of certain whiteflies are attacked by a fungus known as Aschersonia. Both red and brown aschersonia are encountered. This beneficial fungus is often mistaken for scale insectsor plant disease. The fungus will often completely destroy a whitefly population.
This is not a complete list of predators, parasites (parasitoids) , and pathogens. It only covers the most common. For information on other beneficial insects common in your area, contact your local county extension office.
The University of Florida offers four computer-verified training tutorials on beneficial organisms. Information on these tutorials is available on the Buggy Software Web site at http://pests.ifas.ufl.edu/software/det_bugs.htm.