Diseases, pests and beneficial organisms of Strawberry, Raspberry and Blueberry

Diseases, Pests and Beneficial organisms of of

Strawberry, Raspberry, Blueberry

and

Foreword

T

his Guide was created in response to a simple request from strawberry, raspberry and highbush blueberry producers to provide photographs to help them identify problems in their crops. The Guide clearly meets a need and is intended to provide support for the berry industry.

Information on diseases, pests and beneficial organisms has been compiled in a single guide to facilitate crop monitoring and diagnosis. The some 700 illustrations and accompanying descriptions and commentary are in large part a reflection of the actual experiences of professionals, technicians, research scientists and Quebec producers who have worked in the berry industry for 20 years and accumulated extensive experience, diagnosed a multitude of problems and taken vast numbers of photographs. Although the information has particular relevance to the Quebec situation, the authors believe that it should be helpful for growers and advisers of neighbouring Provinces or States.

Diseases, Pests and Beneficial Organisms of Strawberry, Raspberry and Blueberry includes 126 descriptive entries, as well as more general crop monitoring and diagnostic information, basic concepts relative to certain insects and other organisms that may be present in berry crops, information on the phenological stages of the three types of berry crops, and a glossary.

This Guide should help advisers and berry producers to manage their crop timely and appropriately.

ix

Authors and collaborators Diseases Authors Liette Lambert, Agronomist, MAPAQ, Saint-Rémi, Que. Odile Carisse, Ph.D., Plant Pathologist, AAFC, Saint-Jean-sur-Richelieu, Que. Scientific editor Michel Lacroix, Agronomist and Plant Pathologist, Co-ordinator of the Réseau d’avertissements phytosanitaires, MAPAQ, Quebec, Que. Collaborators Nora-Audrey Carisse-Landry, Trainee, AAFC, Saint-Jean-sur-Richelieu, Que. Annie Lefebvre, Technician, AAFC, Saint-Jean-sur-Richelieu, Que. Diane Longtin, Secretary, MAPAQ, Saint-Rémi, Que. Cyril Parris, Trainee, MAPAQ, Saint-Rémi, Que. Daniel Rolland, Technician, AAFC, Saint-Jean-sur-Richelieu, Que.

Pests and beneficial organisms Authors Liette Lambert, Agronomist, MAPAQ, Saint-Rémi, Que. Ginette H. Laplante, Agri-Food Technologist, MAPAQ, Saint-Hyacinthe, Que. Charles Vincent, Ph.D., Agronomist/Entomologist, AAFC, Saint-Jean-sur-Richelieu, Que.

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Scientific editors Michèle Roy, Ph.D., Agronomist/Entomologist, MAPAQ, Quebec, Que. Mario Fréchette, Wildlife Technician, MAPAQ, Quebec, Que. Collaborators Nathalie Laplante, Biologist, MAPAQ, Saint-Hyacinthe, Que. Diane Longtin, Secretary, MAPAQ, Saint-Rémi, Que. Pierre Lemoyne, M.Sc., Technician, AAFC, Saint-Jean-sur-Richelieu, Que. Sébastien Morneault, Trainee, MAPAQ, Montérégie, Que. Gaétan Roberge, Project Leader, AAFC, Saint-Jean-sur-Richelieu, Que. Judith Villegas, Entomologist, MAPAQ, Saint-Hyacinthe, Que. Marina Violette, Trainee, MAPAQ, Saint-Rémi, Que.

Editing and co-ordinating Danielle Jacques, Agronomist, M.Sc., Publications Project Leader, Centre de référence en agriculture et agroalimentaire du Québec (CRAAQ), Quebec, Que. Lyne Lauzon, Biologist, Publications Co-ordinator, CRAAQ, Quebec, Que. Sylvie Robitaille, Computer Graphics Technician, CRAAQ, Quebec, Que.

Page layout Agriculture and Agri-Food Canada (AAFC)

xii

Acknowledgements

T

he CRAAQ wishes to thank all of the following organizations, without whose support this Guide would not have been possible:

We would also like to thank all of the following indi­ viduals and organizations who helped from near and far to produce this Guide: Guy Bélair, Nematologist, AAFC, Saint-Jean-sur-Richelieu, Que. Josée Bonneville, Agronomist, Dura-Club, Que. André Carrier, M.Sc., Agronomist, MAPAQ, Que. Dominique Choquette, Agronomist, Club agroenvironnemental de l’Estrie, Que. Jean Coulombe, M.Sc., Agronomist, R&D Consultant, Que. xiii

Nathalie Dauphinais, M.Sc., Technician, AAFC, Saint-Jean-sur-Richelieu, Que. François Demers, Agronomist, Les Productions Écolo Max Inc., Que. Yvon Fournier, Technician, AAFC, Saint-Jean-sur-Richelieu, Que. Myriam Gagnon, Agronomist, Dura-Club, Que. Eric Hanson, University of Michigan, MI, USA Sandra Hindson, M.A., AAFC, Saint-Jean-sur-Richelieu, Que. Frédéric Laforge, M.Sc., Agronomist, Phytoclone, Que. Lise Lapointe, Blueberry Producer, Que. Michel Lareau, M.Sc., Agronomist, Consultant and Producer, Que. Pierrette Lavoie, Agronomist, Dépistage écologique de la Mauricie Inc., Que. Paul Legault, Berry Producer, Que. Simon Parent, Technician, Novafruit inc., Que. André Payette, Insectarium de Montréal, Muséums nature Montréal, Que. Marvin P. Pritts, Cornell University, Ithaca, NY, USA Martine Robert, La Financière agricole du Québec, L’Assomption, Que. Danielle Roy, Agronomist, MAPAQ, L’Assomption, Que. Pierre O. Thibodeau, Ph.D., Agronomist and Plant Pathologist, MAPAQ, Que. Roger Tremblay, Agronomist, Government of New Brunswick, Fredericton, N.B. Lisa Wegener, Consultant, B.C. Blueberry Council, B.C.

Sources of photographs and illustrations Canadian Food Inspection Agency (CFIA) Agriculture and Agri Food Canada (AAFC) Olivier Aubry, Que. Alain Bardet, Centre technique interprofessionnel des fruits et légumes (Ctifl), Paris, France xiv

Guy Bélair, AAFC, Que. Louis Bergeron, MAPAQ, Que. Biobest Canada Ltd. Josée Bonneville, Dura-Club, Que. Denis Bouchard, Que. Lina Breton, Ministère des Ressources naturelles et de la Faune du Québec (MNRF), Que. Jean Brodeur, Research and Development Institute for the Agri-Environment (IRDA), Que. Odile Carisse, AAFC, Que. Jérôme Carrier, MAPAQ, Que. Cho-Kaï Chan, Canada Ent., Vancouver, B.C. Dominique Choquette, Club agroenvironnemental de l’Estrie, Que. Bernard Drouin, MAPAQ, Que. Don P. Elliot, Applied Bio-Nomics, B.C. Gillian Ferguson, Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), Ont. Myriam Gagnon, Dura-Club, Que. Gérard Gilbert, MAPAQ, Que. Eric Hanson, University of Michigan, MI, USA Vincent J. Hickey, Kennebunk, Maine, USA Sandra Hindson, AAFC, Que. Koppert Biological Pierre Lachance, MAPAQ, Que. Christian Lacroix, FERTIOR, Que. Gaétan Laliberté, Dura-Club, Que. Laboratoire de diagnostic en phytoprotection (MAPAQ), Que. Liette Lambert, MAPAQ, Que. Jean-François Landry, AAFC, Ont. Ginette H. Laplante, MAPAQ, Que. Nathalie Laplante, MAPAQ, Que. Michel Lareau, Blueberry Producer, L’Acadie, Que. Alexandre V. Latchininsky, Association for Applied Acridology International, University of Wyoming, WY, USA xv

Richard Lauzier, MAPAQ, Que. Pierre Lemoyne, AAFC, Que. Stéphane Lessard, Que. Kelvin Lynch, New Brunswick Department of Agriculture and Aquaculture, N.B. Serge Mantha, Club de production pomicole de la région de Québec, Que. Jim Matteoni, Kwantlen University, B.C. Ministère de l’Agriculture, des Pêcheries et de l’Alimentation du Québec, Que. Sébastien Morneault, Que. Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), Ont. Thérèse Otis, AAFC, Que. Jacques Painchaud, MAPAQ, Que. Simon Parent, Novafruit inc., Que. André Payette, Insectarium de Montréal, Muséums nature Montréal, Que. Robert E. Pfadt, Wyoming Agricultural Experiment Station (Field Guide to Common Western Grasshoppers), WY, USA Marvin P. Pritts, Department of Horticulture, Cornell University, Ithaca, NY, USA Gaétan Racette, AAFC, Que. David Raworth, AAFC, B.C. Martine Robert, MAPAQ, Que. Françoise Rodrigue, CET-Horticulture-Saguenay–Lac-Saint-Jean, Que. Anne-Laure Sallier, IRDA, Que. Léo-Guy Simard, AAFC, Que. Syngenta Bioline Luc Urbain, MAPAQ, Que. Johanne Vary, MAPAQ, Que. Charles Vincent, AAFC, Que. Lisa Wegener, B.C. Blueberry Council, B.C. Anne Weill, Que.

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Table of contents Foreword....................................................................ix Authors and collaborators..........................................xi Acknowledgements...................................................xiii Explanation of the fact sheets................................. xxii Where, when, and what to look at? What to note?..... xxv Main types of larvae of insects that undergo complete metamorphosis.................. xxxi How to distinguish between hemiptera (Heteroptera) and homoptera larvae..................... xxxii How to distinguish between mites, spiders and small insects................................................. xxxiii Strawberry diseases and pests Phenological stages.................................................... 2 Scouting table for the main strawberry pests............. 3 Diagnostic key for strawberry..................................... 4 Diseases

Anthracnose fruit rot........................................... 9

Powdery mildew................................................12

Aster yellows, green petal and

multiplier disease.............................................15

Viral diseases....................................................19

Gray mold ........................................................20

Slime mold.......................................................23

Leather rot (Crown rot).....................................24

Black root rot....................................................27

Red stele root rot..............................................30

Leaf spots........................................................33

Verticillium wilt.................................................48

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Pests

Redheaded flea beetle......................................51

Strawberry bud weevil......................................53

Meadow spittlebug ...........................................56

Strawberry root weevil and black vine weevil.....58

Strawberry rootworm........................................61

Potato leafhopper.............................................63 Springtails....................................................... 65

Locusts and grasshoppers................................67

Gall wasps........................................................70

June beetles (May beetles)................................71

Strawberry seed beetle.....................................73 Slugs................................................................75 Mammals.........................................................77

Noctuids, cutworms, armyworms.....................79

European earwig...............................................82

Strawberry aphid..............................................84

Tarnished plant bug..........................................87

Rose chafers.....................................................90

Cyclamen mite..................................................91

Click beetles (wireworms).................................94

Two-spotted spider mite...................................96

Western flower thrips........................................99 Leafrollers......................................................101 Raspberry diseases and pests Phenological stages................................................106 Scouting table for the main raspberry pests...........107 Diagnostic key for raspberry...................................108 Diseases Anthracnose...................................................112

Powdery mildew..............................................115

Spur blight......................................................118

Fire blight.......................................................121

Gray mold ......................................................124

Phytophthora root rot.....................................127 xviii

Late leaf rust..................................................131

Raspberry leaf spot........................................134

Crown gall and cane gall.................................136

Verticillium wilt (bluestem).............................140

Viral diseases..................................................143 Pests

Rednecked cane borer....................................148

Redheaded flea beetle....................................150

Raspberry cane borer.....................................152

Strawberry bud weevil....................................155

Raspberry fruitworm.......................................157

Meadow vole (field mouse)............................ 159

Strawberry root weevil....................................161

Potato leafhopper...........................................163

Gall wasps......................................................165 Crickets..........................................................167

Raspberry cane maggot..................................170

Four-spotted sap beetle (picnic beetle).......... 172 Aphids............................................................174

Tarnished plant bug........................................175

European corn borer.......................................177

Raspberry crown borer...................................179

Japanese beetles............................................181

Blackberry skeletonizer..................................183

Wireworms (Click beetles)..............................185

Raspberry sawfly............................................187

McDaniel spider mite......................................189 Blueberry diseases and pests Phenological stages................................................194 Scouting table for the main blueberry pests...........195 Diagnostic key for blueberry...................................196 Diseases

Anthracnose fruit rot.......................................200

Powdery mildew..............................................204

Twig blight......................................................207 xix

Gray mold ......................................................210

Stunt disease..................................................213

Mummy berry.................................................215

Witches’ broom..............................................219

Leaf rust.........................................................221

Sooty blotch...................................................223

Leaf spots......................................................224

Crown gall......................................................227

Viral diseases................................................. 230 Pests

Meadow vole (field mouse).............................240

Blueberry midge.............................................241

Heath spittlebug.............................................242

White-tailed deer.............................................244

Plum curculio.................................................245

Redhumped caterpillar...................................248

Write-marked tussock moth............................250

Fall webworm................................................. 251 Leafhoppers....................................................253

Blueberry tip borer.........................................255

Terminal borers..............................................256 Ants................................................................258

Blueberry stem gall wasp...............................260

June beetles...................................................262

European fruit lecanium.................................265

Snowshoe hare...............................................267 Slugs..............................................................268

Eastern tent caterpillar...................................270

Forest tent caterpillar......................................272

Blueberry leafminer........................................274

Blueberry maggot...........................................275

Copper underwing (rear-humped caterpillar,

pyramidal fruitworm moth).............................278

Cherry fruitworm............................................279 Birds...............................................................282 xx

European earwig.............................................284

Lesser appleworm..........................................286

Blueberry bud mite.........................................289 Aphids............................................................291

Cranberry fruitworm.......................................293

Cecropia moth................................................296

Rose chafer.....................................................297

Japanese beetle..............................................298

Click beetles (wireworms)...............................300

Oblique-banded leafroller................................302 Beneficial organisms

Predatory mites..............................................306 Spiders...........................................................309

Green and brown lacewings............................311

Lady beetles, ladybirds...................................313

Parasitoid wasps.............................................316

European mantid............................................319

Predatory flies................................................320 Pollinators......................................................324

Predatory bugs...............................................330 Glossary.................................................................333 References..............................................................342

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Explanations of the fact sheets

T

his guide provides, for each of the three crops (strawberry, raspberry and blueberry), two series of factsheets, one on diseases and one on pests. A third series of factsheets deals with beneficial organisms in all three crops.

Diseases and pests The factsheets generally include the following information: English name (and synonym, if any) French name Latin name (and synonym, if any) Type of organism (fungus, bacteria or other) in the case of diseases Order: Family, in the case of pests Pictogram indicating risk, frequency and distribution (see table on opposite page). The mention “varietal� indicates that certain cultivars are more susceptible to the disease.

Illustration of the main location of symptoms on the plants Size and appearance of the pest at various stages of development Description of the symptoms and damage Problems that should not be confused with the disease or pest Life cycle of the pest Conditions favourable to development Host plants (pests) Timing and method of scouting Best practices xxii

Risk, frequency and distribution – Explanation of pictograms Risk associated with the presence of the disease or pest

Frequency of the problem

Indicates that there is a hazard, risk of harm to crops or risk of a negative effect on crop development Indicates that it is important to be vigilant and watch for the appearance and development of the problem

Extent of the problem in the field ( )

•

1 dot: Isolated problem R: Rare O: Occasional F: Frequent ?: Frequency unknown in Quebec

Indicates that there is no risk or impact on the crop or crop yield

2 dots: Localized problem, but present at more than one location 3 or 4 dots: Problem that can spread throughout the field

interpretation Examples : F

Problem needs to be monitored, is frequent and can spread throughout the field

R

Problem can cause considerable damage when present but occurs rarely and is localized and scattered (at more than one site in the field)

O

Problem does not pose a risk to the crop, appears only occasionally and is isolated.

Beneficial organisms Beneficial organisms, or beneficials, are grouped according to the order (Acari, Coleoptera, Diptera, etc.) and family that they belong to. The following information is generally provided within these categories: Genus and species (where applicable) Size and appearance at various stages of development Insects and other organisms on which the beneficial organism feeds xxiii

Life cycle Practices for promoting the development of the beneficial organism

Other symbols Organism not visible to the naked eye (primarily mites) Organism commercially available (beneficials)

xxiv

PESTS

STRAWBERRY

F

Strawberry bud weevil Anthonome du fraisier Anthonomus signatus Coleoptera: CurculionidĂŚ

A

Size Adult: 2.5 mm Larva: 0.3–0.6 mm Egg: 0.5 mm

Appearance Egg: Whitish (C).

Larva: Creamy white, C-shaped body; legless; brown head (B).

Adult: Globular body with a long snout (rostrum) that measures almost half the body length (A). Red-brown elytra with two large, round, black median spots that are sometimes rimmed with white scales.

Damage Peduncles and flower buds cleanly cut (D).

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STRAWBERRY

PESTS

B

C

Life cycle  One generation per year. Adults overwinter at the base of hedgerows, in mulch and sheltered places, inside or outside the strawberry field. In May, females bore a hole in the flower bud and lay an egg there. They then cut off the peduncle, which dries out, and the bud drops to the ground. Adults can also eat the flower bud and pierce holes in the sepals. Larvae feed on the flower bud for approximately three weeks. Three larval stages. Adults emerge from the bud in midsummer and feed on the pollen of other host flowers in the fall before seeking an overwintering site.

Favourable conditions  Populations increase as the strawberry field ages. Plants growing under covers or at the edges of fields are at risk.

Host plants Wild strawberry, raspberry, blackberry, blueberry, Parthenocissus (Virginia creeper).

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STRAWBERRY

PESTS

D

Scouting  Adults are particularly active at the end of the day (after 6 p.m.), in calm, dry, sunny weather (temperature above 16°C). Starting when buds become visible and continuing to the end of the flowering period, tap flower clusters over a container, and count the number of adults and cut-off buds. Freshly cut buds (still green) indicate a high risk. Since damage appears suddenly, it is recommended that scouting take place at least twice a week during the flowering period.

Timing of controls The appearance of holes in the sepals (E) indicates an imminent risk. Initiate control as soon as cutE off flower buds or weevils appear, particularly when good weather is forecasted. Treatment can also be initiated at the threshold of three weevils or cut-off buds per 50 taps.

Best practices Do not keep strawberry fields in production for more than two years. Rotate crops far away from strawberry fields in production. Remove weeds growing in and around strawberry fields, particularly pollen-generating plants. Look for damage and respond rapidly.

Photos A and B: Bernard Drouin, MAPAQ; C: Pierre Lachance, MAPAQ; D and E: Liette Lambert, MAPAQ

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PESTS

Crickets

F

RASPBERRY

Grillons Snowy tree cricket (grillon de Fulton) Œcanthus fultoni Four-spotted tree cricket (grillon à quatre points) Œcanthus quadripunctatus Black-horned tree cricket (grillon à cornes noires) Œcanthus nigricornis

Orthoptera : Gryllidæ

A

Size Adult: 20–25 mm Larva: 6–25 mm

Appearance Egg: Cylindrical; cream-coloured or yellowish (A). Laid in symmetrical rows inside canes.

Larva: Upon emergence (B), the young larva is pale yellow and almost transparent. Slender, smooth body.

The more mature larva resembles the adult but without wings (C).

Adult: Elongate. Yellowish to pale green. Long legs. Welldeveloped hind femurs. At rest, wings lie flat against the body. Antennae almost twice as long as the body. The male is slender (D), while the female is rounded (D).

167

PESTS

RASPBERRY

Damage The female chews the bark and inserts rows of eggs (E, F). These punctures prevent sap from flowing up and weaken the cane. In the spring, the leaves and fruits can continue to develop, but the affected canes dry out (G, H) before the fruits reach maturity. The canes also break easily at the weak point where the oviposition holes have been pierced.

Do not confuse The damage with canes dried out by frost, broken by winds or infected with the fungus Phytophthora (no characteristic oviposition holes).

B

The insect with the larvae of plant bugs or leafhoppers (short antennae), adult field crickets (black), or locusts and grasshoppers (larger and stouter).

Life cycle C

Male

Female

One generation per year. Eggs are laid in August and September and overwinter inside canes. Each row can contain up to 80 eggs. Eggs hatch in June. Young larvae feed on leaves throughout the summer and can also feed on aphids and other small insects. Five larval stages before the adult stage in August.

Starting in mid-August, during the mating season, males emit a highpitched noise in the evening and at night.

Best practices  Prune affected canes in the spring, before hatching occurs, and immediately burn the prunings.

D 168

RASPBERRY

PESTS

E

F

G

H Photos A, B, D, E, F, G and H: Liette Lambert, MAPAQ; C: Ginette H. Laplante, MAPAQ

169

DISEASES

B LU E B E R RY

R

Viral diseases Maladies virales Viruses

I 

n North America, a number of viruses infect blueberry and can cause a significant reduction in productivity of susceptible cultivars. In Quebec, however, only a few viral diseases have been diagnosed, the most recent being blueberry scorch virus (BIScV).

The most frequently encountered virus in blueberry fields in Quebec is tomato ringspot virus (ToRSV).

Several cultivars are very susceptible to this virus. It is therefore advisable to destroy these plants and plant a tolerant or resistant cultivar. This virus is transmitted by soil nematodes, Xiphinema spp. These roundworms, which are invisible to the naked eye (2 mm long), move very slowly between soil particles through water films.

These ectoparasites transmit the virus by perforating the wall of root cells in order to feed. That is why the infection site increases in size very slowly each year (e.g.

1 m in diameter per year).

Symptoms The symptoms of the various viral diseases are provided in the tables on pages 236 to 239.

Do not confuse Damage: Winter frost (more-generalized damage), spring frost (early in the season), anthracnose fruit rot (symptoms on the berries), mummy berry (mummified berries), gray mold (down-like gray fungus), deficiencies in minerals such as boron, potassium or magnesium (slightly more-generalized damage), excessive water inducing iron deficiency (damage localized to areas where water accumulates), June beetles (larvae near roots), phytotoxicity caused by herbicides (e.g. clopyralid, dichlobenil, glyphosate, simazine) or other 230

DISEASES

B LU E B E R RY

chemicals such as fluorine (more-generalized damage without varietal effect), high salinity (generalized damage), various types of leaf spots (rarely cause dwarfing or dieback).

Best practices There is no remedy against viruses, and some cause more damage than others, depending on varietal susceptibility, the type of damage that the viruses cause, and the presence of vectors that can quickly transmit the viruses from plant to plant. All viruses are transmissible through propagation of infected plants by cuttings, hence the importance of obtaining virus-free plants. As a precaution, it is advisable to disinfect tools after pruning suspicious-looking plants. Contamination can be limited by controlling the vectors (nematodes and aphids). Adequate control of weeds, especially dandelion and plantain, is important since these weeds often harbour Xiphinema, which transmits ToRSV. Remove and burn affected plants, including the root system, which can also remain infected. Avoid planting near an infested blueberry field. If in doubt, send a sample to your Provincial or State diagnostic laboratory, if available, accompanied by a soil sample, preferably collected in late May/early June, in order to detect and count nematodes.

231

DISEASES

B LU E B E R RY

Tomato ringspot virus (ToRSV)

A

B

C

D

E

F

G

H

I 232

DISEASES

J

K

L

M

N

O

P

Q

B LU E B E R RY

Blueberry scorch virus (BlScV)

R 233

B LU E B E R RY

DISEASES

Blueberry shoestring virus (BBSSV)

Blueberry leaf mottle virus (BBLMV)

S1

S2

T

Red ringspot virus (RRSV)

234

U

V

W

X

DISEASES

Tobacco ringspot virus (ToRSV)

B LU E B E R RY

Mosaic virus

Z1

Y

Z2

Photos A, B, C, E, F, G, H and I: Liette Lambert, MAPAQ; D: Ginette H. Laplante, MAPAQ; J, K, L, M, N, O, Q and R: Lisa Wegener; P: David Raworth, AAFC; S1, S2, T, U, V, W, X, Y and Z2: Marvin P. Pritts, Cornell University; Z1: Eric Hanson, University of Michigan

235

BENEFICIAL ORGANISMS

Lady beetles, ladybirds Coccinelles Coleoptera : Coccinellidæ

A

Size

B

Adult: 1–10 mm Egg: Eggs laid in clusters (10 to 50 eggs) on foliage (A, B).

Appearance Larva: Resembles a small black crocodile (C), often with spots whose shape and pattern vary depending on the species (C, D).

Pupa: Immobile and attached to plants by the tip of the abdomen (E).

Adult: Bright colouring, variable depending on the species. Coloured patterns visible a few hours after emergence. The most common lady beetles include the pink-spotted lady beetle (D, F, K), the seven-spotted lady beetle (G), the fourteen-spotted lady beetle (H) and the Asian lady beetle (I). The colour and number of spots on the Asian lady beetle are highly variable, but the species is distinguished by the M- or W-shaped marking on the top of the thorax.

Diet Most species feed primarily on aphids, whereas others, such as Stethorus punctillum, prefer mites, such as spider mites.

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BENEFICIAL ORGANISMS 7 to 10 mm

C

D

E

F

G 4 to 6 mm

H

Life cycle  Lady beetles overwinter in the adult stage, singly or in groups. Some species, such as the pink-spotted lady beetle, gather in large numbers under leaves or in leaf litter, often in woodland edges or under large trees. Others, such as the fourteen-spotted lady beetle (H), are arboreal and are observed in blueberry and raspberry fields. Of the 77 species surveyed in Quebec, the Asian lady beetle, introduced into Louisiana in 1988 and reported in Quebec in 1994, is the only species that has become a pest by moving indoors in the fall to survive the winter and feeding on certain juicy fruits, such as raspberries. A wasp, Dinocampus coccinellae (J), sometimes parasitizes lady beetles, and its pupae can be seen (K) on the underside of the pink-spotted lady beetle’s body.

314

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7 to 10 mm

K

BENEFICIAL ORGANISMS

I

J

L

M

N Adult and pupa

Adult newly emerged from its pupa

Spider mite predatory beetle

Stethorus punctillum spp.

The oval eggs are whitish in colour and turn black immediately prior to emergence of the larvae (L). The pupa is black and hairy, like the adult (M). Upon emergence, the adult is light-coloured (N), darkening O within several hours (O). It is often confused with other small black beetles such as flea beetles, which hop. Under the magnifying glass, flea beetles are hairless, whereas S. punctillum is pubescent.

Photos A, C, G and H: Nathalie Laplante, MAPAQ; B, D, E, F, I, K and M: Liette Lambert, MAPAQ; J: Ginette H. Laplante, MAPAQ; L, N and O: Biobest Canada

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