Facts, Identification & Control
Various species of coneworm moths are very different in their appearance and host plant preferences, therefore providing a simple description of coneworm adults and larvae is extremely difficult. However, all coneworm species go through four developmental stages in their life cycle: eggs, larvae (caterpillar), pupae (cocoon) and adults. Adult moths are small and seldom noticed. Signs of a coneworm infestation include mats of frass held together by silk webbing on the outside of cones, plus circular larval exit holes in cones.
Behavior, Diet & Habits
Coneworm larvae infest the cones and seeds of numerous species of coniferous trees such as pine, fir, spruce, Douglas fir and hemlock. In addition, coneworms infest cypress and hickory tree nuts. Adults are active at night and highly attracted to light. Larvae usually feed internally on the host plant’s cones or nuts, but may also feed on needles and twigs. Larvae do not damage trees, but cause a huge amount of damage by destroying seeds and cones. Some species are very mobile and will feed on more than one cone. Feeding larvae damage ranges from tunnels to completely excavated cavities in cones and nuts. The adults lay eggs under the scales of new cones or under the tree’s bark. Larvae feed during the summer months and drop to the ground to overwinter in either the last larval (prepupae) or pupal stage. As the weather warms in the spring, adults emerge, mate and the female moth lays eggs. Eggs hatch about one month later and larvae begin boring into and feeding on cones and nuts. Generally, coneworm species have only one generation per year.
Other than commercial seed production nurseries, there are very few reasons to use insecticides for coneworm control. So, before using an insecticide, first check with your pest management professional and get professional help and advice on whether and how to employ control products. Suggested proactive techniques that enhance and maintain tree health and vitality are helpful to lessen the likelihood of a coneworm infestation.