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Learn Your Lawn: Cranberry Girdler

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The Cranberry Girdler is a member of the sod webworm family, commonly found in the northern United States and Canada. It is often misdiagnosed due to its resemblance to a White Grub. The most obvious difference between the two is that the Cranberry Girdler is generally smaller and does not have visible brown legs like those of a White Grub.  


When it comes to damaging your lawn, the larvae are the primary culprits. They feed on the stems and roots of grass plants, causing sections of grass to turn brown and die. The adult Cranberry Girdler Moth is grayish-brown in colour and about 1/2 inch long when fully grown. 




The life cycle of the cranberry girdler is typically completed within one year, although, in some cases, it may take up to two years. The severity of the damage caused by the larvae can vary depending on the population of the moths, weather conditions, and other factors. 

  • Egg Stage: Adult moths lay their eggs in the late summer or early fall. The eggs are small, white, and oval-shaped, and typically hatch within a week.

  • Larva Stage: The newly hatched larvae have an ivory-yellow colour with a brownish-black head. As they grow, they become darker in colour and develop distinctive dark stripes along their bodies. The larvae feed on the leaves and stems of the grass, often causing significant damage.

  • Pupa Stage: In the spring, the larvae pupate in cocoons made of silk and plant debris. The pupal stage typically lasts for about two weeks.

  • Adult Stage: The adult moths emerge from their cocoons in the late spring or early summer. They are a brownish-gray colour with distinctive markings on their wings. The adult moths do not feed on the turf, but instead mate and lay their eggs, starting the cycle all over again.




The best time to control the Cranberry Girdler is early in their life cycle, before severe damage occurs. A change in cultural practices can help deter infestations of this pest. However, if damage becomes severe, other forms of control may be necessary.


A thick, healthy, well-maintained lawn is always the best line of defense. This can be achieved through beneficial cultural practices, which include:

  • Watering: Deep and infrequent watering is essential for strong plant health and development. A general rule of thumb is to water each area of your lawn for 30-45 minutes, twice per week, in the early morning so the turf is dry by nightfall. 

  • Mowing: Maintain a regular mowing schedule throughout the growing season. In general, you should keep your lawn between 2 ½ and 3 ½ inches high, but during the hottest weeks of summer, you may allow the grass to grow as high as 4 inches. Never remove more than ⅓ of the grass blade at each mowing.

  • Fertilizing: Regular applications of Weed Man’s specially formulated, slow-release granular fertilizer will help provide your lawn with adequate nutrients. These applications are timed specifically to avoid over fertilizing the lawn.

  • Core Aeration: Aerating your lawn can improve soil drainage and help reduce the likelihood of insect infestations. It will also alleviate soil compaction and allow water and nutrients to penetrate deeper into the soil.


Your local Weed Man professional may be able to offer other solutions and recommend the best form of treatment that is available to improve the conditions of your lawn.