Beneficial Insects
From BugwoodWiki
Authors' Note: Some insects cause no damage to crops, and are considered beneficial because they feed on various pest insects. Since they are found in association with the various pest insects on which they feed, they can be identified on a wide variety of crops.
Lady Beetles: Convergent, Pink, Twice-Stabbed
These include:
- Convergent Lady Beetle (Hippodamia convergens)
- Pink Lady Beetle (Coleomegilla maculata)
- Twice-Stabbed Lady Beetle (Chilocorus stigma)
Several species of lady beetles are commonly found in crops with the convergent and the pink lady beetle being the most abundant. Adults are small, about 1/4 inch (6 mm), rounded with brightly colored backs. Larvae are usually carrot-shaped, warty and have well-developed legs. Larvae may be up to 3/8 inch (9 mm) in length and variously colored with black, blue, orange, and red.
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Spiders: Green Lynx Spider (Peucetia viridans) and others
Many types of spiders are found in fields and vary greatly in size and color. Spiders are general feeders and will attack or capture any insect they encounter. Spiders are one of the few beneficials that may be found in a field that has been treated with insecticides. Although spiders are not normally abundant in a field, they contribute to the overall natural suppression of pests.
  Photo by Herbert A. "Joe" Pase III, Texas Forest Service, Bugwood.org |  Photo by Sturgis McKeever, Georgia Southern University, Bugwood.org |  Photo by Merle Shepard, Gerald R.Carner, and P.A.C Ooi, Insects and their Natural Enemies Associated with Vegetables and Soybean in Southeast Asia, Bugwood.org |
Lacewings: Goldeneye Lacewing (Chrysopa oculata)
Several species of lacewings are found in fields with the goldeneyed or green lacewing being most common. Adults are smaller and fragile with large membranous green wings. Larvae are brown and white, about 1/2 inch (12 mm) long and resemble lady beetle larvae. They can be distinguished by their large, forward projecting mandibles. Lacewing eggs are often found on plants and are easily recognized since they are attached to a long slender filament which holds them above the plant surface. Only the larvae are predaceous.
 Photo by Clemson University - USDA Cooperative Extension Slide Series, , Bugwood.org |
Wasps: Braconid spp., Ichneumonid spp.
Several species of small parasitic wasps may be seen in fields. Adults range in size from very tiny to 1/2 inch (13 mm) in length. Color also varies, but many are brightly colored. Wasps are often seen flying in and out of the plant canopy searching for host insects on which to lay eggs. Larvae of parasitic wasps develop within the body of the pest insect, ultimately killing the host.
 Photo by Scott Bauer, USDA Agricultural Research Service, Bugwood.org |  Photo by Johnny N. Dell, , Bugwood.org |
Big-Eyed Bugs (Geocoris spp.)
The adult is shiny black and white and slightly less than 1/4 inch (6 mm) in length. The nymph is gray and wingless. Both adults and numphs have large, bulging eyes.
 Photo by Whitney Cranshaw, Colorado State University, Bugwood.org |  Photo by Bradley Higbee, Paramount Farming, Bugwood.org |
Syrphids (Syrphidae)
Adults resemble small bees while larvae are green or yellow, legless, rather flat maggots about 3/8 inch (9 mm) long. Only the larvae are predacious and may be found crawling on undersides of leaves.
 Photo by David Cappaert, Michigan State University, Bugwood.org |  Photo by Merle Shepard, Gerald R.Carner, and P.A.C Ooi, Insects and their Natural Enemies Associated with Vegetables and Soybean in Southeast Asia, Bugwood.org |  Photo by David Cappaert, Michigan State University, Bugwood.org |
Ground Beetles (Carabidae)
Adults range in size from about 1/2 to 1 1/2 inches long (13-38 mm) and are usually dark brown or black. Several species have numerous small iridescent spots on their backs. Larvae are dark, wormlike, and have well developed legs and mandibles. Ground beetles are often active at night and may be numerous at times.
Assassin Bugs (Reduviidae)
There are several species of insects collectively called assassin bugs which range in length from 1/2 to 1 1/2 inches long (13-38 mm). Many are brown or black with bright colored markings on the back. These bugs have a prominent beak, small head, and a "neck." Assassin bugs are seldom present in large numbers.
 Photo by Susan Ellis, , Bugwood.org |  Photo by Whitney Cranshaw, Colorado State University, Bugwood.org |
Nabids (Nabis spp.)
Adults are about 1/2 inch (13 mm) and light brown. They are slender and have long legs and beaks. Nabids are commonly seen in fields that have not been sprayed with insecticides, but are usually not found in large numbers.
