CDFA Pest Prevention Plant Regulation Practice Exam

In which stage does the grape leaf skeletonizer overwinter?

1. pupa

2. larva

3. adult

4. egg

The correct answer is: pupa

The grape leaf skeletonizer, a pest that affects grapevines, overwinters in the pupal stage. This stage is crucial for the pest's life cycle because it is a phase of relative dormancy where the insect can withstand adverse environmental conditions. During winter, temperatures drop, and food resources become scarce, making the pupal stage an effective means for the grape leaf skeletonizer to survive until favorable conditions return in spring. In this stage, the larvae have already undergone several instars and have transitioned into a form that is encased and more resilient to cold weather. Once conditions improve, usually with warmer temperatures and the availability of host plants, the pupae will emerge as adults, ready to mate and continue the cycle. In contrast, while larvae and eggs are also stages in the life cycle of pests, they are not capable of surviving through harsh winter conditions as effectively as pupae. The adult stage is focused on reproduction and feeding rather than overwintering. Therefore, the pupa stage is specifically adapted for enduring the winter months, making it the correct answer for this question.