Common strawberry insects and their control

Publication 990

December, 1956

COMMON STRAWBERRY INSECTS
AND THEIR CONTROL

by
H. ANDISON

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SCIENCE SERVICE, ENTOMOLOGY DIVISION
CANADA DEPARTMENT OF AGRICULTURE

•2—12:56

Digitized by the Internet Archive

in 2012 with funding from

Agriculture and Agri-Food Canada - Agriculture et Agroalimentaire Canada

http://www.archive.org/details/commonstrawberryOOandi

COMMON STRAWBERRY INSECTS AND THEIR CONTROL

BY HARRY ANDISON
Entomology Laboratory, Victoria, British Columbia

In Canada strawberries are seriously attacked by comparatively few-
insects, and if the general practices given below are followed the necessity
for control measures may often be avoided. It should be noted, however, that
strawberry insect problems differ in various parts of the country, and that
practices considered good in one locality may not be satisfactory or may have
to be modified in another locality. For example, early spring burning of the
plantation is widely practised in the Maritime Provinces to control the straw-
berry fruit bug and other pests but is not considered advisable in Ontario or
British Columbia. Also, in certain areas of British Columbia the root weevils
may require control measures every year, whereas in Ontario these are not
necessary until an outbreak occurs. For these reasons only a general account
can be given here and growers are urged to consult local agricultural authorities
for further details.

General Practices

1. Set out only healthy plants.

2. Plant on land previously occupied by hoed crops that have been kept
free from weeds. Avoid planting on land that was in sod the previous year.

3. Set new plantings as far as possible from old ones.

4. Keep the field free from weeds and grass and clean up any surrounding
rough land; destroy wild brambles, raspberries, and thickets that may provide
shelter for harmful insects.

Key to Species Causing Damage

The key given below is an aid to quick diagnosis of insect injury, but
control measures should not be undertaken until the grower feels assured,
from reading the full text, that the description fits his particular case. If in
doubt send a sample of the insect and its damage to the Crop Insect Unit,
Entomology Division, Canada Department of Agriculture, Science Service
Bldg., Ottawa. Samples up to 12 oz. in weight may be sent through the mail
free of postage.

Injury to Blossom Buds

Blossom stems cut, causing the buds to wilt, drop off, or hang by a

thread Strawberry weevil, p. 6

Injury to Fruit

Berries distorted or malformed, developing into so-called nubbins

Meadow spittlebug, p. 10

Strawberry fruit bug, p. 6

Tarnished plant bug, p. 7

p.

7

p.

9

p-

19

p.

10

p.

8

4

Holes eaten in ripening fruit Strawberry chlamys, p. 19

Round holes eaten in ripe fruit Strawberry root weevil, p. 14

Injury to Leaves

Holes eaten in leaves by small, shiny beetles, giving the foliage a

"shot holed" appearance Strawberry leaf beetle, p. 7

Leaves folded, usually along the midrib, by small greenish or
brownish caterpillars that feed within the shelters thus formed

Strawberry leaf roller,

Whitish or yellowish speckling on the foliage .... Spider mites,

Leaves chewed and plants defoliated by rose-colored grubs in black
dome-shaped cases Strawberry chlamys,

White masses of spittle on leaf stems and other parts of plants

Meadow spittlebug,

Leaves chewed during the night by smooth, stout caterpillars that
hide under the soil by day Cutworms,

Leaves in center of plant inrolled, crinkled, and deformed

Cyclamen mite, p. 10

Notches eaten in edges of leaves Strawberry root weevil, p. 14

Black vine weevil, p. 17

Plants stunted, leaves and blossom trusses deformed . . Shallot aphid, p. 20

Injury to Crowns

Small, pink caterpillars boring in crown

Strawberry crown miner, p. 20

Larger, whitish caterpillars boring in crown

Strawberry crown moth, p. 18

Injury to Roots

Large whitish grubs, with six distinct legs, eating the roots and

killing the plants White grubs, P- 11

Large, whitish grubs, without legs, feeding on rootlets and weaken-
ing or killing the plants Strawberry root weevil, p. 14

Black vine weevil, P- 17

Thin, shiny brown larvae feeding on roots Wireworms, p. 18

Injury to Collar

Plants cut off near ground level by smooth, stout caterpillars that

hide under the soil by day Cutworms, p. 8

Figure 1. — 1. Work of the strawberry leaf beetle. 2. White grub. 3. Strawberry root weevil.
4. Cutworm. 5. Work of the strawberry weevil.

77775—2

Strawberry Weevil

Anthonomus signatus Say

This insect, a very small, reddish brown or blackish snout beetle, approxi-
mately -^ inch long, may very seriously reduce the crop by cutting off
unopened blossom buds. Occasionally it attacks blackberry and raspberry.

The beetles begin to appear in the spring when the first few strawberry
blossoms open. Their presence at this time is indicated by small round holes
that they eat in the petals. The presence of these holes should warn the
grower to keep a close watch on the plantation and to prepare for spraying or
dusting the plants. The female weevil punctures the side of an unopened
blossom bud and inserts an egg into the interior of the bud. She then crawls
down the stem a short distance, girdles it, and leaves the bud hanging by a
thread or severs the stem completely so that the bud falls to the ground
(Fig. 1(5)). The egg hatches, the larva develops inside the bud, and a new
beetle comes out in July about the time the crop has been harvested. There
is but one generation a year, and the new beetles hibernate in the plantation
itself and in brambles or hedgerows of wild and escaped raspberry canes that
may be growing in the vicinity.

Control

As soon as bud-cutting begins, dust the plantation with a 3 per cent DDT
dust. Apply the dust with a power duster or a good hand blower, preferably
in the morning when the dew is going off and when there is little or no wind.
DDT may also be used as a liquid spray applied as soon as the first blossom
petals showing typical weevil injury are found. Use 50 per cent wettable
DDT, 2 lb. in 100 gal. of water.

Injury from this insect may be reduced and sometimes prevented by
clearing up all thickets, bushes, fence rows, and wild strawberries and
raspberries near the strawberry plantation. Set out new plantings as far as
possible from the old. The practice in the east of cleaning up old plantations
by burning them over in the early spring affords little or no control of this
insect.

Strawberry Fruit Bug

Calocoris norvegicus (Gmelin)

In Nova Scotia, and possibly elsewhere, this small, active, green bug
frequently causes extensive damage to the developing fruit by sucking the
juices from it. In severe cases the fruit may fail to develop, but in lighter
infestations the berries may be distorted or malformed, developing into
so-called nubbins. The bugs, in both the mature and immature stages, are
very active and furtive and are not likely to be observed unless a careful
search is made. For this reason the damage caused by this insect is usually
attributed to some other agency such as frost or imperfect pollination.

Though a complete study of the life-history of this insect has not yet
been made, observations indicate that the winter is passed in the egg stage.
The eggs are deposited in the stems of the strawberry plants and also some
weeds, including sheep sorrel, one of the insect's favored food plants. The
young bugs appear in the spring soon after the first blossoms open and may
begin stinging the fruit as soon as it starts to form. About the time the fruit
is ripe the bugs are full-grown, and they soon leave the strawberries and may
be found on a number of plants, including many field and garden crops, grasses,
and weeds.

Control

Spray with 50 per cent wettable DDT, 2 lb. in 100 gal. of water, when
the first blossoms appear. Keeping the plantation free from weeds, especially
sheep sorrel, will help in control.

Tarnished Plant Bug

Lygus lineolaris (Beauv.)

This common bug attacks many plants and in several provinces has
caused damage to strawberries very similar to that of the strawberry fruit
bug. The major damage is caused by the adults and nymphs sucking the
juices from the developing buds and berries, resulting in a hard, malformed
fruit that is unfit for sale.

The adults are brownish, flattened, oval in outline, and about £ inch long.
They overwinter under leaves and debris and emerge in the spring to feed
and lay their eggs on a great variety of plants. There are at least two
generations each season.

Control

Plantations and their surroundings should be kept free of weeds. A spray
of 50 per cent DDT, 2 lb. in 100 gal., when the first blossoms appear will give
commercial control.

Strawberry Leaf Beetle

Paria canella (F.)

In spring and autumn, strawberry plants are occasionally attacked by a
dark-brown or black, shiny, oval-shaped beetle about | inch long that eats
holes in the leaves, giving them a lacework effect (Fig. 1(1)). This insect
feeds also on raspberry, blackberry, greenhouse roses, and some other plants.

The beetles hibernate among old leaves, straw, or trash, and as soon as
growth commences in the spring they feed voraciously on the leaves. Eggs
are laid in the soil close to the crowns of the plants and on the undersides of
dead leaves lying around the plants. The very small larvae that hatch from
these eggs burrow into the soil and feed on the rootlets of the strawberry
plants, where they may cause considerable injury when present in sufficient
numbers. When full-grown the larvae are about g inch long. They then
pupate in the soil, and the new beetles emerge from about the end of July
to September. After feeding for a while the beetles go into winter quarters.

Control

It is seldom necessary to spray for the control of this pest. If the beetles
are very abundant they may be controlled by spraying thoroughly with either
5 lb. of lead arsenate or 3f lb. of calcium arsenate, or 2 lb. of 50 per cent
wettable DDT powder in 100 gal. of water. This spray should only be applied
before blossoming, or after the crop has been picked. DDT may cause
mites to become abundant.

Strawberry Leaf Roller

Ancylis comptana fragariae (W. & R.)

Several species of leaf rollers with similar habits attack strawberries but
the only one of economic importance is the strawberry leaf roller. The presence
of leaf rollers can readily be detected by the folded leaves within which the
larvae feed.

77775— 2i

8

The strawberry leaf roller winters in the larval stage in the folded leaves.
In the spring the larvae pupate and transform to small, inconspicuous moths
with a wing expanse of about \ inch. The eggs, which are not readily observed,
are laid singly on the leaves. On hatching, the larvae feed on the leaves and
soon begin to tie and fold them together. They feed within the shelters thus
formed and are protected from most poison sprays. When full-grown the
larvae are about \ inch long, very active when disturbed, and of a greenish
or brownish color. The larvae pupate and change to moths in July and early
August. These lay eggs for the second generation, the larvae of which feed
from August until stopped by cold weather.

Control

The following practices help to reduce the numbers of leaf rollers and
lessen the need for chemical control: As soon as the last crop has been
harvested, plow the plants under; set new plantings as far as possible from
old ones. Use uninfested plants or, when setting out the plants, pinch folded
leaves to kill the larvae within. Mowing the planting after harvest helps to
reduce leaf roller infestations.

A spray of 1| lb. of 15 per cent wettable parathion or of 2 lb. of 50 per
cent wettable DDD (TDE) in 100 gallons of water, or a dust of 7 per cent
DDD is effective if thoroughly applied. Two hundred gallons of spray or 25
lb. of dust are required per acre for each application. Parathion gives better
control than DDD if many larvae have folded the leaves before the spray is
applied. The treatments should be applied as follows in areas where the leaf
roller has been troublesome: —

(a) New plantings (non-bearing). — For the first brood apply two sprays
or dusts 10 days apart, starting the first or second week in June. If these sprays
are not applied, or if the infestation is very heavy, spray twice, 10 days apart,
for the second brood, starting about August 15.

(b) Bearing Plantings. — As injury by the first generation is seldom serious
on bearing plantings, spraying or dusting is not usually recommended. How-
ever, for heavy infestations, a spray of DDD applied just as the first blossoms
open gives some protection. In order to protect bees, and to avoid spray residues,
poisons should not be applied during the bloom and fruiting periods.

If the planting is to be kept for another season's crop, the second generation
may be controlled by spraying or dusting about August 15 and again 10
days later.

Cutworms

Several species of cutworms may cause much damage in strawberry
plantations by cutting off the new plants at ground level and by chewing
the foliage of older plants. In general, most cutworms are similar in appear-
ance, being smooth, cylindrical caterpillars about an inch long and of a dull
earth color (Figure 1(4)). They feed during the night and hide in the soil
during the day. Cutworms usually cease causing damage before the end of
June. The adults are drab-colored moths that fly during the night and are
often attracted to lights.

Control

The following poisoned bait controls cutworms: —

Bran 25 lb.

Paris green 1 lb.

Water about 2\ gal.

Mix the bran and poison; then add water slowly to this mixture while
stirring. Scatter the bait thinly on the ground after sundown, along the rows
where the cutworms are present. It is important that this should be done
in the evening and only after a warm day. Fifteen pounds of bait will treat
about an acre. Where cutworms are abundant, one baiting may not be suffi-
cient. Proprietary baits containing apple waste are effective in controlling
most species in British Columbia.

For a new planting that will not be cropped until the next year, a grower
may prefer to spray or dust. Spray with 50 per cent wettable DDT, 2 lb. in
100 gal. of water, or dust with a 3 per cent DDT dust. It is essential to apply
the control measures early in the spring to kill the immature caterpillars before
they cause extensive damage.

In plots where cutworms are present, it is advisable to broadcast baits
on a warm evening, or dust with DDT a few days before setting out the plants.

Spicier Mites

Spider mites, commonly known as 'red spiders', are occasionally trouble-
some pests of strawberries. They are more likely to be abundant if DDT
is applied early in the season. The two-spotted spider mite, Tetranychus
bimaculatus Harvey, occurs in practically all strawberry-growing areas.

Mite injury is first apparent as very fine whitish or yellowish speckling
on the foliage. This is caused by the mites sucking out the juices, giving the
foliage a pale, unhealthy appearance. Later the leaves may turn brown and
drop. The undersides of the leaves are covered with a fine silken web,
beneath which the mites may be seen as tiny moving dots. Injury is usually
most severe in hot, dry weather.

The adult mites are about 1/50 inch long; during most of the season they
are pale greenish yellow but in the fall or on badly injured foliage they may
be orange-red. They overwinter under trash and in the soil about the bases
of the plants. When growth starts in the spring they crawl up to the leaves
and commence to lay eggs on the undersides. The mites that hatch from these
eggs mature rapidly in warm, dry weather and in turn lay eggs that produce
more mites. There may be as many as 10 generations a year in the warmer
parts of Canada.

Control

If spider mites are easily found, or if the leaves show spotting from their
feeding, spray with TEPP, Aramite, or Ovotran, diluted according to the
manufacturer's directions. Do not use TEPP or Aramite with hydrated lime
or bordeaux mixture. TEPP spray has to be repeated in 7 to 10 days, and
the other materials may require a second application. A coarse, driving spray
at high pressure gives the best coverage of the undersides of the leaves.

Aramite and malathion have been used successfully as sprays or dusts in
British Columbia.

Non-bearing patches may be sprayed at any time. If it is necessary to
control mites during harvest, pick the fruit closely, spray with TEPP, and do
not pick for at least two days. Follow the same procedure for a second
spray 7 to 10 days later.

10

Cyclamen Mite

Tarsonemus pallidus Banks

This mite is not uncommon on strawberries in many sections of Canada
but only occasionally causes sufficient damage to be noticed by the grower.
On infested plants the unopened leaves turn yellowish, then brownish, and
may die, or if they open they remain crinkled and deformed. The mites can
scarcely be observed with the unaided eyes but can be found with a magnifying
lens if the young, unopened leaves are unrolled so as to expose them. Since
the symptoms are not clearly marked in the early stages, the presence of the
mites is the only certain criterion.

The mites shun the light and prefer the seclusion of the folds of unopened
leaves, where they feed and lay their eggs. As the leaves expand, the mites
avoid exposure by moving to younger, unopened leaves. In these and the
crowns they pass the winter, and begin feeding and reproducing the following
spring.

Control

The only effective control measure known at the present time is to dip
the young plants in hot water before they are set out in the spring. Experiments
have shown that plants should be immersed in water at a temperature of 110°F.,
but not higher, for 20 minutes. After this they should be quickly cooled by
plunging them into a bath of cold water. To ensure control it is recommended
that if the plants are tied into bundles (25-50) the strings should be cut before
dipping; otherwise the temperature in the center of the bundle will fail to
reach 110°F., or will reach it so slowly that not all of the mites will be killed.
It is most important that the temperature of the water be held at 110° during
the entire period of immersion, for if the temperature reaches 115° the plants
will be killed and if it falls to 107° the mites will not be killed. A reliable and
easily read thermometer should be used and the water kept stirred to ensure
even temperature throughout. Plants should be set out as soon as possible
after treatment. It is particularly important that stock plants sold to growers
should be free from this mite.

Meadow Spittlebug

Philcenus leucophthalmus (L.)

This insect commonly attacks weeds and other plants but occasionally
appears on strawberries in sufficient numbers to reduce the crop and weaken
the plants. Injury is most marked when an infestation coincides with a
dry season.

The eggs, the stage in which winter is passed, are probably laid on the
leaves and stems of the plants. They begin to hatch about the time the earliest
strawberry blossoms appear, and the young nymphs feed on the plants by
piercing the tissue and sucking out the plant juices in much the same way as
aphids. Very soon the nymphs are surrounded by drops of clear liquid and
later by considerable amounts of white spittle. They are most commonly
found on and between the flower-bud clusters when the latter are still compact,
on leaf stems, and on the young growth of the crown. Each spittle mass may
contain one or more nymphs. The nymphs develop into adults about the time
the crop is harvested. The adults both fly and hop, are usually dull brown, and
are about \ inch long. There is only one brood a year.

11

Control

Once the spittle masses appear, the nymphs are well protected and control
is difficult. Where it is known, from the previous year's experience, that an
attack is likely to occur, the plantation should be sprayed, as soon as the earliest
blossoms appear, with 50 per cent wettable DDT, 2 lb. in 100 gal. of water.
Sufficient pressure must be used to drive the spray into the compact, young
growth.

White Grubs

Polyphylla perversa Csy.
Phyllophaga spp.

White grubs, the larvae of the well-known June beetles (or June 'bugs'),
are the large, stout, grayish white grubs, usually curved in an almost complete
circle when at rest, that are frequently found feeding on the roots of straw-
berries (Figure 2). They either kill or severely weaken the plants and are
most destructive where strawberries are planted after sod. A striped June
beetle, Polyphylla perversa Csy. (Figure 3), is confined to British Columbia and
there are a number of species of Phyllophaga in Eastern Canada.

Figures 2 and 3.— The striped June beetle that commonly attacks strawberry in British
Columbia. Male (left), female (center), and grub (right).

The white grubs that occur in the mid-west and Eastern Canada are
usually destructive to strawberry only in Ontario and Quebec. They have
a 3-year life-cycle and the adults occur in peak numbers in only one year
out of three, their occurrence depending on the district. Most damage is done
by the second-year grubs, and therefore serious injury may occur every third
year.

The beetles of the eastern species appear in early summer and commonly
fly about in the evening and at night, particularly about trees on the leaves
of which they feed. They lay their eggs in soil covered with vegetation,
chiefly on grass land. The eggs hatch and the tiny grubs feed on the roots
of plants until late autumn, when they burrow deeper into the soil and remain
dormant until the following spring. During their second summer they feed
and again return to the deeper soil in the autumn to spend the winter. The
third spring some of the grubs return to the roots near the surface for a short
while before pupating and changing into beetles in late summer. Others
remain in the subsoil and change into beetles in the autumn. The beetles do
not leave the soil until the following spring.

12

In British Columbia, the striped June beetle has a similar 3-year life-
cycle but all stages are found in considerable numbers each year and
injury may occur each year. Although damage by the second-year grubs is
usually the most serious, third-year grubs do more feeding than the species
occuring in the east.

Control

In British Columbia, during the past several years very satisfactory
results have been obtained in field experiments in controlling white grubs in
the soil. Four new and promising soil insecticides, aldrin, chlordane, dieldrin,
and heptachlor, give good control under field conditions. These materials are
available in Canada under various brand names. Where fields are known to
be infested, apply one of these insecticides to the soil before plowing, and also
dust the roots of the plants before planting.

1. Soil Treatments before Planting. — The amount of each formulation to
use per acre to give the proper amount of actual insecticide is shown in the
following table: —

Formulation

Amount per Acre

Aldrin
5 lb. (actual)

Dieldrin
4 lb. (actual)

Chlordane
10 lb. (actual)

Heptachlor
4 lb. (actual)

Dust 2\%

5%

Wettable powder 25%

50%

Emulsifiable) 20%

Concentrate) 65%

200 lb.
100 "

20 "
10 "

10 qt.

160 lb.
80 "

16 "

8 "

2 gal.

200 lb.

40 "
20 "

5qt.

160 lb.
80 "

16 "

8 "

2 gal.

Whatever material is used, distribute it evenly over the soil and immedi-
ately (1) work it in with a rotary cultivator or (2) plow it in to a depth of 6
to 8 inches, and then disk the land thoroughly. Where small plots are to be
treated, use a small, hand-drawn fertilizer cart or spreader to apply the dusts
(Figure 5). Where larger acreages are involved, use a large fertilizer or lime
spreader that can be readily adjusted and pulled over the field by tractor
(Figure 4). The insecticides may also be sprayed evenly over the soil before
plowing (Figure 6). This method of application gives the most even distribu-
tion of the insecticide. Spray equipment for this type of application is described
in Canada Department of Agriculture Processed Publication Series, Entomology,
No. 119. By operating a rotary pump from the tractor power take-off and
adjusting the spray boom to cover a 45-inch spray swath, you may obtain
complete soil coverage. The spray boom should have six flat-type nozzles,
each 9 inches apart and 6 inches above the soil surface. The nozzles should
have disk apertures of 0-04 inch. By travelling at 2 • 5 m.p.h. and operating
the pump at 100 pounds per square inch, you may apply approximately 200
gallons of spray per acre.

Results indicate that these materials are effective when applied at any
time of the year, and they have not adversely affected the growth of strawberry
plants. All four insecticides have a residual effect, each remaining toxic to
white grubs for at least 3 years. No tainting of the fruit has resulted from the
large-scale commercial use of these materials in British Columbia during
the past 5 years.

13

2. Plant Treatments before Planting. — Dust the roots of the plants before
planting. Puncture the lid of a 20-ounce jar or tin can with a 2-inch nail
to make a "salt shaker" type of container for applying the dust to the roots.
Use approximately 6 pounds of 2\ per cent aldrin, dieldrin, or heptachlor dust

Figure 4 and 5. — Combination drill for dusting large acreage and lawn-cart fertilizer spreader

for small plantings. These may be used to apply insecticidal dusts to soil surface before

plowing to a depth of 6 to 8 inches. To apply insecticides at 200 pounds per acre, adjust holes

in bottom of fertilizer spreader to remain half-open.

14

or 5 per cent chlordane dust per acre of strawberries, or 1 ounce per 100
plants. This treatment also gives immediate protection from root weevils
and wireworms.

Recommendations for controlling white grubs in Eastern Canada are as
follows: Do not plant strawberries on grub-infested soil or on land that was
in sod the previous year. Frequent cross-disking before planting will reduce
the number of grubs. Insecticides may be used before plants are set out in
years when the destructive second-year grubs are present. Find out from
your agricultural extension service which years these are. The amount of
actual insecticide to use per acre is: (1) heptachlor, 3 lb. (2£ per cent dust at
120 lb. per acre); (2) aldrin, 3 to 5 lb. (2£ per cent dust at 120 to 200 lb.

Figure 6. — Row-crop sprayer. This may be used to spray the surface of the soil with insecticide

before plowing. The spray boom has 6 flat-type nozzles, each 9 inches apart and placed 6 inches

above the soil level. The nozzles have disk apertures of 04 inch. Operating at 100 pounds

per square inch and travelling at 2-5 m.p.h. the sprayer applies 200 gallons per acre.

per acre); or (3) chlordane, 5 to 10 lb. (5 per cent dust at 120 to 200 lb.
per acre). The larger amounts are for heavy soils. They should be evenly
distributed over the soil and immediately worked into the top 3 to 4 inches
before planting. Granular dusts are preferred as they spread more readily.
The materials may also be applied as sprays by adding the proper amount of a
spray powder or emulsifiable formulation to a tank of water and spraying it
evenly over the soil to give the right amount per acre.

Strawberry Root Weevil

Brachyrhinus ovatus (L.)

The strawberry root weevil, though widely distributed in Canada, ranks
as a serious pest of strawberries chiefly in British Columbia, where it is most
prevalent on light or sandy soils. The adult — a small, dark beetle (Figure 7),
egg-shaped in general outline and about | inch long — nibbles strawberry leaves
(Figure 8); but the all-important injury is caused by the small, white, legless
grubs feeding on the roots (Figure 9), thus weakening or killing the plants.
(See also "Black Vine Weevil".)

This species usually overwinters in the soil as half-grown larvae among
the roots of the plants. In the spring the larvae form earthen cells and change

15

to pupae. They remain as pupae for about 3 weeks and then develop into adults
during early June, when the British Sovereign strawberry commences to ripen.
After feeding for about 2 weeks they begin to lay their eggs on the ground
near the crowns of the plants. The eggs usually hatch in about 10 days.
The young larvae, on hatching, burrow into the soil to a depth of 6 to 10
inches and feed on the fibrous roots.

I

Figure 7. — Adults of the black vine weevil (right) and the strawberry root weevil (left)

Length of line indicates actual size.

Figure 8. — Strawberry leaves attacked by adults of the strawberry root weevil.

A small percentage of these root weevils spend the winter as adults in
the soil. They usually emerge about mid-April to continue laying eggs
during May and June.

16

Control

Weevil injury may be greatly lessened by setting out new plantings as
far as possible from old ones; by planting strawberries after a non-host crop
such as potatoes, mangels, or similar hoed crops; and by avoiding planting
after grass or clover sod. Where the plantation has become infested, satisfactory
control may be obtained only by the use of a poisoned bait.

Apply baits to kill the strawberry root weevil adults before they lay their
eggs; and when an infestation is severe it is advisable to apply them twice, once
about mid-April to kill the overwintering adults and again during June, when
the overwintering larvae develop into adults. The June treatment is the main

Figure 9.— Strawberry plant showing result of attack by grubs or the strawberry root weevil.

poisoning operation and, if poisoned bait is to be used at all, should not be
delayed. Proper timing, which is essential to ensure good results, may be
accomplished as follows: —

(1) Mid- April: Examine the leaves frequently for the ragged-edge effect
resulting from the beetles' feeding on them. When "ragging" is observed
(adults can be found in the soil at the bases of the plants at this time),
apply the bait.

(2) June 10 to 30: Examine the soil about the crowns of the plants for
presence of adult beetles. When "ragging" of the leaves is observed, apply
the bait. Very often holes eaten in the ripe fruits by the beetles can also
be seen at this time.

Closely examine plants bordering on old plantings, fence rows, or sod
land where weevils are abundant. Locate heavily infested areas early and
bait them to prevent the spread of weevils to the remainder of the crop field.

Apply one tablespoon of bait per plant (hill system), taking care that
the mixture falls to the ground close to the crown rather than on growing
foliage or tender stems. Make the application during dry, warm weather if
possible. Use about 80 to 100 lb. of bait to treat 1 acre.

17

1. Baits. — Proprietary baits consisting of ground apple waste and sodium
fluosilicate have given satisfactory results in British Columbia. Do not apply
them too dry; add water to moisten if necessary. If you prefer to mix your
own bait, use the following formula: —

Bran 50 lb.

Water 5 gais.

Sugar (or stock molasses, used with less water) 10 lb.

Sodium fluosilicate 5 lb.

Dissolve the sugar in water; then mix the solution with the bran until it is
uniformly moistened; add the poison and thoroughly mix again. Use the
bait within a day or two after mixing or it will mold and lose its effectiveness.

2. Soil and Plant Treatments before Planting. — Where white grubs, the
black vine weevil, or wireworms are also a problem, apply aldrin, dieldrin,
chlordane, or heptachlor to the soil and to the roots of the plants before plant-
ing. Any one of these insecticides controls all four insect species for at least
3 years. The methods and rates of application are the same as outlined in the
section on white grubs.

Black Vine Weevil

Brachyrhinus sulcatus (F.)

The life-history and habits of this insect are much the same as those of
the strawberry root weevil, but the black vine weevil is much larger (Figure 7)
and seems to prefer heavier types of soils. During the past 3 years it has
become a major problem in British Columbia, especially on farms where
irrigation or sawdust mulch are being used.

The adults emerge approximately 2 weeks later than those of the straw-
berry root weevil and are mainly foliage feeders.

Control

Baits do not control this weevil. Damage can be greatly lessened by

setting out new plantings as far from old ones as possible and by avoiding

planting after grass or clover sod. Where fields are known to be infested,
use the following control measures: —

1. Soil and Plant Treatments before Planting. — Where possible, apply
aldrin, dieldrin, chlordane, or heptachlor to the soil and to the roots' of the
plants, before planting. The methods and rates of application are the same
as for white grubs. For details refer to page 12.

2. Plant Treatments after Planting.— If the soil or the plant roots are
not treated, dust or spray the foliage of the plants three times each year with
aldrin, heptachlor, or chlordane. Make the first application in late April
before blossoming, the second in early July (immediately after strawberry
picking is completed), and the third 3 weeks later. It is most important to
make an application in early July, when the overwintering grubs have
developed into adults and before egg-laying has started. Dust with either 2h
per cent aldrin or heptachlor, or 5 per cent chlordane, using about 25 pounds
per application per acre of strawberries, or a quarter of a pound per 100
plants. The most suitable equipment for applying these materials to row
crops such as strawberries is a duster of the bellows or puff type.

Sprays applied to the foliage should contain 1 quart of 24 per cent aldrin
or heptachlor or 1 pint of 65 per cent chlordane per 100 gallons. Apply about
200 gallons of spray per acre of strawberries each time.

18

When handling these chemicals wear an approved respirator and rubber
gloves. Under no circumstances dust or spray an edible crop such as straw-
berries with aldrin, heptachlor, or chlordane after the fruit has formed.

For further information see ''Control of Root Weevils in British Columbia",
Processed Publication Series, Entomology, No. 78, Canada Department of
Agriculture, Ottawa.

Wireworms

Of the various species, the one that most commonly causes damage to
strawberries in British Columbia is the Puget Sound wireworm, Ctenicera
aeripennis aeripennis (Kby.) Figure 10. The adults are commonly called click
beetles and their life-history is similar to that of white grubs. Damage usually

Jk±

Figure 10. — Wireworms are yellowish-brown, shiny, slender, hard-bodied 'worms' with three
pairs of short legs. When full-grown, many species are about an inch long

and as thick as a match stick.

results when strawberries are planted after sod. Excellent control of wireworms
has been obtained by applying aldrin, dieldrin, heptachlor, or chlordane, as
recommended for the control of white grubs and root weevils. In the East,
however, no control measures have been necessary to date beyond that of
avoiding the planting of strawberries on land that was weedy or in sod the
previous year.

Strawberry Crown Moth

Ramosia bibionipennis (Bdvl.)

The adults are clear- winged moths resembling small yellow jackets
(Fig. 12). They can be found resting on the foliage, or flying close to the
ground. The full-grown larva is about f inch long, with a dark-brown head
and white body. However, when the larva is half-grown the abdomen
assumes a pink color, as a result of eating root tissue.

The adult moths commence to emerge from the strawberry crowns about
mid-July. Eggs are laid singly on the undersides of old or new leaves next
the crown. As the eggs hatch, the larvae enter the crown, where they

19

tunnel within the tissue for the remainder of the summer (Fig. 11). They
over-winter as nearly full-grown larvae and commence feeding again in the
spring. When mature the larva develops a silken cocoon, which protrudes
slightly outside of the crown of the plant at soil level. From the pupa en-
closed in the cocoon, the adult emerges and the one-generation cycle is
repeated.

Figure 12. — Adult female of the strawberry
crown moth. Magnification l£x.

Figure 11. — Larva of the strawberry crown

moth and damage caused to the crown of

the plant. Natural size.

Control

Remove and burn infested plants in the spring, before the moths emerge.
Burn or mow the tops after strawberry harvest.

Strawberry Chlamys

Chlamisus fragariae Brown

This species, a new pest recently found in southwestern New Brunswick,
is capable of causing severe defoliation of strawberry plantations. Although
the adults feed freely in the spring and fall, the most serious damage is
done by the larvae, which feed voraciously on the leaves and commonly
attack the ripening fruit.

The adult is a shiny bronze beetle, cubical in shape, about \ inch long.
The rose-colored larvae are enclosed in a black dome-shaped case, resembling
the burnt head of a match. When the grubs feed, only their mouth parts
and thoracic legs protrude from the case.

20

Eggs on tiny stalks and covered with a protective case of excrement
are laid singly on the undersides of the leaves during late May and early
June. The eggs hatch in about 12 days and the larvae feed until the end
of July and then pupate. Adults emerge from mid-August till the end of
September and are active in the plantation until cold weather forces them
into hibernation.

Control

A pre-blossom application of 3 per cent DDT dust at 40 pounds per
acre provides effective control. A second application after picking time is
recommended, particularly on new plantings.

Strawberry Crown Miner

Aristotelia fragariae Busck

This insect is established in the coastal areas of British Columbia and
in Ontario. The small, carmine pink larvae bore into the crown, causing
severe stunting and usually complete destruction of the plant.

The mature larvae overwinter in silken cases in the strawberry crowns.
Pupae develop early in the spring and the small gray moths emerge during
mid-June. Eggs are laid during the latter part of June and early July. Most
of the eggs hatch during mid-July or immediately after picking has been
completed. The newly emerged larvae wander over the leaf surfaces a short
time before they bore into the crown just below the bases of the leaves.
Feeding continues throughout the summer until the larvae reach maturity
in September.

The strawberry crown miner is rarely troublesome where a short rotation
is followed and new plantings are set some distance from old ones. Chemical
control experiments conducted in Iowa, U.S.A., indicate that 5 per cent
DDT dust applied immediately after harvest (July 15) gave good control
of this species.

An Aphid

Myzus ascalonicus Doncaster

In 1955 an aphid, known in Great Britain as the shallot aphid, was
recorded as a pest of strawberries for the first time in North America. It
caused serious losses on several farms in southern Vancouver Island and
the lower Fraser Valley, B.C.

This aphid is pale greenish brown in color and feeds on the young leaves
and blossom trusses as soon as they develop from the crown. Attacked plants
are dwarfed, with crinkled or curled leaves and blossoms. When the aphids
are numerous this serious damage can be seen from mid-April to early May.
Injury is most severe after a mild winter and spring. It is first noticed on
small, circular patches of plants, and gradually spreads until the entire
planting is affected.

In late May or early June, all the newly developing aphids have wings
and migrate to unknown hosts. During October, winged aphids return to
the strawberry plants and deposit living young that do not develop wings.
Throughout the autumn, winter, and early spring, all the aphids produced
are wingless.

21

Control

Examine the strawberry planting during mid-April for signs of leaf
curling and aphids feeding on the undersides of the new leaves. Spray
twice at two-week intervals, commencing during the third week of April,
with 50 per cent malathion emulsifiable concentrate at 2 pints per 100 gallons
of water. For best results use 200 pounds' pressure per square inch and
3 nozzles per row.

LIBRARY LWi'SSHSiMI

All8Sft8?SSB; OTTAWA K1A 0C5

3 =1073 QQQbHHOE 5

EDMOND CLOUTIER, C.M.G., O.A., D.S.P.

QUEEN'S PRINTER AND CONTROLLER OF STATIONERY

OTTAWA, 1956

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