Aphid Biology, Monitoring and Control

All About Aphids: biology, monitoring, control J.D. DeAngelis, consulting entomologist www.LivingWithBugs.com Aphid biology is extremely varied and com- plex. They cause damage in conifers both directly and indirectly. Direct damage comes from feeding injury and plant growth defor- mities. Indirect damage comes mainly from aphid honeydew and organisms associated with this honeydew. May, 2005

se pesticides sparingly and wisely. Pesticide information is based on US product Ulabels available at the time of the last update. The laws in your area may be different. Where differences occur your local laws take precedence. Please read and follow product labels that are appropriate for your area. You are responsible for the safe and legal use of pesticides. Pesticide toxicology information in the US can be found at National Pesticide Information Center (http://www.npic.orst.edu) or 1-800-858-7378. These contacts should not be used in an emergency. In an emergency contact your local poison control office or emergency system.

1:30 - 1:45 aphid types, life cycles & damage 1:45 - 1:55 conifer aphids 1:55 - 2:10 adelgids 2:20 - 2:30 break 2:30 - 2:45 control options 2:45 - 3:00 questions & answers 3:00 - 5:00 field scouting Handouts* Aphid & Adelgid Pests of Conifers EC 1444 (1994) Root Aphid Handout (1998) Balsam Woolly Adelgid & Balsam Twig Aphid (1998) LWB Annual Christmas Tree Pest Update (2005) *download at www.livingwithbugs.com/com_note.html

Copyright 2005 LivingWithBugs.com Aphids are ... • soft-bodied insects that feed on plants by piercing and sucking • no pupal stage, incomplete metamorphosis • rapid population growth, both sexual and asexual reproduction • adelgids are conifer-feeding aphids in genus Adelges • while feeding may inject host with toxins and pathogens • honeydew is excreted because plant sap is low in nitrogen • honeydew attracts other insects and supports growth of fungi • many natural enemies

Copyright 2005 LivingWithBugs.com Douglas-fir •Cinara (bow-legged fir) aphids •Cooley spruce gall adelgid (secondary host) dark crawlers early season, white-waxy adults later (galls on spruce) True Firs •Cinara (bow-legged fir) aphids •Balsam twig aphid (Fraser, grand) small aphids cause twisting of needles, mat needles together with honeydew and wax •Balsam woolly adelgid (noble) swelling of branch nodes, waxy covering on bark in heavy infestations •Root aphids - see 1998 handout

Copyright 2005 LivingWithBugs.com Cinara, or bow-legged fir, aphids on true fir. These aphids occur on all conifers. Different species occur on different host plants. These aphids tend to be large, dark in color and generally not covered by wax. Cinara aphids excrete large amounts of honeydew. Unless the infestation is extremely large these aphids probably do little other than produce honeydew that attracts yel- lowjackets and sooty mold.

Copyright 2005 LivingWithBugs.com Cinara aphid colony on young noble fir. Hon- eydew from these colonies support yellow- jackets and sooty mold. Large colonies may weaken trees. Generally no control is neces- sary beyond spot treatment.

Copyright 2005 LivingWithBugs.com Cooley spruce gall adelgid on Douglas-fir. Adel- gids cover themselves with white waxy secre- tion. Injected toxins may cause bent and distorted needles. Dark grey or black crawlers appear at budbreak. Crawlers should be targeted in any control effort. Scout- ing should begin prior to budbreak.

Copyright 2005 LivingWithBugs.com Cooley spruce gall adelgid on spruce. Spruce is the primary host for this adelgid. “Primary host” means that the sexual population occurs on this host tree. Cross-section of spruce gall. These galls form at branch tips. Adelgids enter at needle bases and induce gall formation. These “pineapple” galls may last several years but don’t otherwise harm trees.

Copyright 2005 LivingWithBugs.com Close-up of hemlock woolly adelgid on hemlock. This adelgid can be a severe pest of hemlock in both forest and landscape trees. However, some varieties of hemlock are moderately resistant. Adelgids feed along stems under white, waxy material.

Balsam twig aphids cause twisting and matting of needles. Matting is caused by wax and honeydew. Infestations may be spotty in fields so spot treatments can be effec- tive.

Balsam woolly adelgids cause swelling at branch nodes in noble fir. Heavy infestations can kill trees.

The key to aphid control in Christmas trees is to scout and spot treat early season infestations. This protects natural enemy populations and controls aphids at exposed stage.

Copyright 2005 LivingWithBugs.com Parasitic wasp and aphid “mummy”. These tiny wasps lay eggs inside live aphids. Wasp larvae complete development and emerge as adult wasps. Parasitized aphids swell and often change to a golden color. Parasitic wasps may account for most natural aphid control but usually go unnoticed.

Insecticides for aphids and adelgids Trade Name Manufacturer Uses insecticidal soap various spot treat early season horticultural oil various treat early season contact, good coverage im- Provado 1.6 F Bayer CropScience portant, early season, two applications contact & systemic, rapidly FlagShip 25 WG Syngenta absorbed, expensive Most formulations are RU endosulfan various because of acute toxicity. Doug-fir and PNW only.

Copyright 2005 LivingWithBugs.com Things to consider ... •Cinara aphids - spot treat w/ soap or do nothing. Early season treatment for needle midge may suppress Cinara on Douglas-fir and subsequent yellowjacket populatons. •Cooley spruce gall adelgid (Douglas-fir) - spot treat crawlers at bud break or do nothing. Heavy infestation may require treatment. Needle midge treatment may suppress this adelgid on Dougas-fir as well. • Balsam twig aphid - suppress to control needle matting in fall in trees to be harvested or reduce longer term needle deforma- tion and loss. Early season Provado or Flagship (?). • Balsam woolly adelgid - early season Provado or Flagship (?).