Phylloxera’s Life Cycle and its role in California’s Vineyards
Soon after infestation, the vine will experience stunted growth and develop fewer, unhealthier leaves. Eventually, leaves turn yellow and begin to wither and grapes start to shrivel. The roots initially turn yellow and eventually begin to rot.
Phylloxera has a complex life cycle that I will do my best to explain. In March, the mother emerges from an egg in the ground where she has been dormant for the winter. She lies up to a few hundred eggs that hatch between 6 and 12 days depending on the temperature.
Her offspring begin their lives as yellow larvae that move around on the roots of the vine. As the insects mature, they eventually attach to the roots and eat sap. They dispose of their waste by injecting it back into the roots. This is what adversely affects Vitis vinifera vines.
Each of the offspring will shed their skin on 5 occasions. They get a little darker each time until they are brown. After 3 weeks, the louse is mature and can lay its own eggs. The cycle then repeats until July. A single phylloxera louse can turn into several million in a matter of months.
In July, a different type of insect begins hatching out of the previous generations’ eggs. They are known as nymphs and have wings. These creatures leave the roots and eat sap off the vine itself. They fly as they please until October when they begin inserting 2 different kinds of eggs into the leaves.
The larger eggs become females and the smaller ones become males. The males fertilize the females and they lay eggs in the ground that will be dormant until the next March when a new female emerges, and the cycle repeats.
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