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Damage to the strawberry plant is caused by the larva, which bores and tunnels in the crowns and roots. The larvae may kill plants and can seriously affect yields. It also occurs on and damages blackcap and red raspberries, loganberries, and boysenberries. The native host plant may be either the wild strawberry or one of the wild caneberries.

The adult is a clear-winged moth about 12 mm in length, closely resembling a yellow jacket when in flight. The body is black with yellow bands. The forewings are rather transparent with dark borders; hind wings are transparent with dark veins and fringes of hair. The male is darker than the female and has a fan-shaped tuft of hairs at the tip of the abdomen. The egg is brown, sculptured, and oval with lateral concave depressions. The newly hatched larva is about 4 mm in length and completely white. The mature larva is about 20 mm in length and white with a dark brown head. It may appear red or brown due to the contents of the intestine. The pupa varies from 12 mm to 15 mm in length and is brown with rows of spines on the top of the abdomen. Pupation occurs in a silk cocoon covered with frass.

The SCM overwinters in the crown and roots of the strawberry plant as a dormant larva in a silken cocoon. The larvae leave cocoons and resume feeding in the spring. Pupation occurs in the roots and crown of the plant from May through July. The adults fly from June through July. They mate shortly after emergence and females begin laying eggs singly on stems, leaves, and about the bases of plants. Larvae emerge from the eggs in 10 to 14 days, depending on the temperature, and feed in the crown and roots through the fall. The nearly mature larvae then construct overwintering cells and pass the winter in an inactive state. There are four to six larval instars and one generation per year.

There are no commercial strawberry varieties resistant to the SCM. Previous research by OSU entomologists and grower experience indicate certain cultural practices may be useful in reducing infestations:

1. Untopped strawberry plants can serve as trap plants. If plants are topped before the moth's flight period, a few rows should be left untopped. Egg-laying females are attracted to and deposit a significant portion of their eggs on the untopped plants. These untopped plants are then disked under in the fall.

2. Remove infested plants. Infestations usually begin near field borders and damaged plants occur in clumps. These plants are stunted and develop a reddish color earlier in the fall than noninfested plants. These plants should be removed and destroyed.

3. New plantings should not be placed adjacent to infested fields. Grain planted between a new field and an infested field can serve as a barrier to the flight of the adult moths, thereby preventing infestation of the new field.

4. Plow out infested fields. Thorough shredding of all roots and crowns followed by deep plowing is necesssary to kill the strawberry crown moth larvae and pupae. Do this in August, September, or October.

The SCM is difficult to control for a number of reasons:

1. The flight period may begin as early as the first week in June. Because strawberries may be harvested through the first week in July, infestation occurs during a period that an insecticide is not usually applied.

2. The flight period of the SCM extends through July.

3. Upon eclosion, the newly hatched larvae rapidly bore into plant tissue where they are not susceptible to insecticidal control.

4. Persistent soil-applied chlorinated insecticides that may have offered control of young larvae are no longer registered for use on strawberries.

Insecticides can help to control the strawberry crown moth. They should be applied in approximately 200 gallons of water per acre directed to the crowns as high pressure sprays that thoroughly disperse the chemicals over the crown where newly hatched larvae enter the plants.

Timing is critical. The first application should be made about the time the first eggs begin to hatch. One and possibly two more applications may be needed because of the long period of time (about 2 months) that the egg-laying moths are present. The second application should be made no later than 14 days after the first. The third application, if needed, should be applied 14 days after the second. Rainfall may alter this pattern somewhat.

The first application should be made 10 to 14 days after it has been determined that SCM adults have consistently begun to emerge from pupae. This varies from late May to early June. Pheromone traps are available to determine consistent emergence. These should be placed in two to four locations within a field. Consistent emergence is that point when two or three adults are caught in traps in 2 or more consecutive days.

Endosulfan or azinphos-methyl should be used for the first insecticide application. These materials help to control some of the adults but are primarily used as a crown spray to kill newly hatched larvae beginning to bore into the plant.

The second application should be made 2 weeks later. If harvest is over, the plants should be topped, and Lorsban 4E applied immediately. If harvest is still in progress, then azinphos-methyl or endosulfan (choose the material not used for the first spray) should be applied.

If a third application is required, use Lorsban, which can be used twice postharvest.

Note: Control of SCM larvae is not possible with available insecticides once larvae are established in the roots and crowns of strawberry plants.

However, larvae in caneberries can be controlled, because unlike infestations in strawberries, this pest is exposed on the surface of the root and crown during feeding and development.

Treat raspberries, loganberries, boysenberries, and marionberries growing adjacent to an infested strawberry field using an insecticide drench in the fall or spring. This will protect the caneberries from SCM and reduce migration of the moth from the caneberries to the strawberries. Azinphos-methyl (Sniper ) or diazinon, when applied as a crown drench to control the raspberrry crown borer, also control the SCM.