Beneficial Insects and Spiders of Alaska PMC-10075
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Beneficial Insects and Spiders of Alaska PMC-10075 Cover photos, left to right: Top row: crab spider (Misumena vatia), Dave Guinn; three-banded lady beetle (Coccinella trifasciata perplexa) eating aphids, Aaron Hagerty; green lacewing (Chrysopidae), Dave Guinn Bottom row: parasitoid wasp (Ichneumonidae), Dave Guinn; aerial yellowjacket (Dolichovespula arenaria), Derek Sikes This printing was paid for by the Renewable Resources Extension Act (RREA). www.uaf.edu/ces or 1-877-520-5211 Jessie Moan, Extension Integrated Pest Management Technician. Originally prepared by Michele Hébert, former Extension Agriculture and Horticulture Agent. Published by the University of Alaska Fairbanks Cooperative Extension Service in co- operation with the United States Department of Agriculture. The University of Alaska is an AA/EO employer and educational institution and prohibits illegal discrimina- tion against any individual: www.alaska.edu/nondiscrimination ©2019 University of Alaska Fairbanks. 6-07/MH/9-19 Revised September 2019 Table of Contents Introduction .............................................................................................................................. 1 Beneficial Spiders and Their Relatives ................................................................................... 2 Daddy Longlegs or Harvestman (Order: Opiliones) ........................................................... 4 Wolf Spiders (Family: Lycosidae) ........................................................................................... 6 Crab Spiders (Family: Thomisidae) ....................................................................................... 8 Orbweaver Spiders (Family: Araneidae) .............................................................................10 Beneficial Insects: Introduction ............................................................................................12 Damsel Bugs, Nabids (Family: Nabidae) .............................................................................14 Lacewings (Order: Neuroptera) ...........................................................................................16 Ground Beetles (Family: Carabidae) ...................................................................................20 Lady Beetles (Family: Coccinellidae) ..................................................................................22 Flower Flies (Family: Syrphidae) ..........................................................................................26 Robber Flies (Family: Asilidae) ............................................................................................28 Yellowjackets (Family: Vespidae) .........................................................................................30 Parasitoid Wasps (Order: Hymenoptera) ............................................................................32 Parasitoid Flies (Family: Tachinidae)...................................................................................34 Photo Credits ..........................................................................................................................36 Photo Identifications for Known Taxa .................................................................................37 References ................................................................................................................................38 Acknowledgements ................................................................................................................39 4 Introduction Gardens and agricultural systems sup- Predators hunt and consume other port a community of small invertebrates, species to survive. Insects may be preda- including pests and their natural enemies. tors in either the immature or adult stage Natural enemies are organisms that act or both. Adult parasitoids deposit eggs in, against other organisms in ways that gen- on or near the body of their host. When erally keep populations below damaging the eggs hatch, the larvae feed on the host’s levels. We consider these natural enemies body while it is still alive and eventually to be beneficial organisms in our environ- cause mortality. Adult parasitoids are ments and an important component of generally free-living, feeding on nectar or integrated pest management strategies. pollen. Pathogens are microorganisms Natural enemies are particularly impor- (fungi, bacteria or viruses) that produce tant in low-input and organic systems, disease and lead to death. where they may be a primary component Additional information on identifica- of a pest management program. tion of beneficial organisms and encourag- Natural enemies can be divided into ing and incorporating them into your pest three broad categories: predators, para- management program is available through sitoids, and pathogens. This booklet will your local Cooperative Extension Service cover common predators and parasitoids. office. 1 Beneficial Spiders and Their Relatives Identification actively pursue prey in a hunting manner. Spiders are characterized by having The spiders outlined in this booklet have four pairs of legs and two body regions, been included because of their likelihood the cephalothorax (head and thorax com- to be present in a garden or crop setting in bined) and abdomen, usually separated by Alaska. Exclusion of any family of spiders a waist constriction. does not indicate their absence from the Spiders are distinguished by spinnerets, state or a lack of beneficial qualities. the silk and web-spinning organs at the Attract spiders by providing a variety rear of the abdomen. Spinnerets may or of plant structures that offer harborage may not be immediately visible on all and habitat for them. spiders. Habits All spiders in Alaska are predators, feeding on insects and other small arthropods. Most spiders are docile and harmless to humans. Some spiders construct webs to ensnare prey; others do not spin webs but 2 Beneficial Spiders and Their Relatives 2 3 1 3 Daddy Longlegs or Harvestman (Order: Opiliones) Identification glands that produce strong-smelling Harvestmen species are not true spi- secretions for defense. They deposit their ders but are close relatives of spiders. They eggs in soil, in cracks or crevices and lack a constricted waist and spinnerets. under bark. Harvestmen have a small, pea-sized There are several harvestman species in body and eight slender legs. Legs can be Alaska; they are most frequently found in either long or short. undisturbed forest sites. The upper surface of the body is usu- ally a mottled grey and brown coloration, while the underside is a cream color. Web Type Harvestmen do not spin a web. Habits Harvestmen are generalist predators, feeding on soft-bodied insects, some beetle larvae, slugs and snails, and decaying organic matter. Harvestmen use special 4 Daddy Longlegs or Harvestman (Order: Opiliones) 4 5 5 Wolf Spiders (Family: Lycosidae) Identification rocks or cracks for retreat, while others are Wolf spiders have highly variable grey found in grass, leaf litter or stony areas. and brown color patterns to match their Female wolf spiders carry egg sacs surroundings. They are mostly moderately under their spinnerets. After hatching, the sized spiders with most being approxi- tiny spiderlings climb onto the abdomen mately one inch in length. of the mother, where they remain for a considerable amount of time. Web Type In Alaska, wolf spiders are encountered around the yard and garden and some- Wolf spiders do not spin webs, but times even in homes. females spin silk to make egg sacs. Attract wolf spiders by maintaining a few permanent plantings. Edging, wooden Habits walkways and mulch also provide shelter. Wolf spiders are fast and are often seen running from disturbances or danger. They have excellent eyesight and are active predators. Some species make tunnels in the ground or use natural depressions such as 6 Wolf Spiders (Family: Lycosidae) 6 7 7 Crab Spiders (Family: Thomisidae) Identification prey on the ground. This family of spiders Crab spiders have their first and second relies more on touch than eyesight to pairs of legs much longer than the last two detect prey. pairs, giving them a crab-like appearance. Some species may slowly change color Their abdomen is often much wider to match their flower perch. than it is high. They are usually light in color and rely on camouflage to hunt. Web Type Crab spiders do not spin webs, snares or nests, but they do spin egg sacs. Habits Crab spiders secure their prey by ambush and stealth and can often be found on flowers in the garden setting. Camouflaged, they lie in wait for prey — sometimes for days. They also stalk their 8 Crab Spiders (Family: Thomisidae) 8 9 9 Orbweaver Spiders (Family: Araneidae) Identification Habits Orbweavers are highly varied in size Orbweavers are most famous for their and coloration. The Alaska example shown web engineering. They and their webs are is a large species with a brightly patterned commonly found on or near plants in the abdomen and distinctive leg markings. garden and on the exteriors of homes and Males are often much smaller than decks. females. With greatly reduced eyes, orbweavers rely on the vibration of the web to indicate Web Type when prey has been captured. Orbweavers are so-named because they Females camouflage egg sacs within the construct a web made up of concentric web or sometimes bury them in leaf duff. circles of silk anchored to the surrounding Members of this group are some of the vegetation. largest spiders likely