Why do female Tubulifera thrips lack an ovipositor?

In the suborder Tubulifera, female thrips lack an ovipositor because their reproductive strategy differs from that of the suborder Terebrantia. While female Terebrantia possess a sawlike ovipositor used to insert eggs into living plant tissue, female Tubulifera do not require this specialized structure for egg-laying.123

Instead of cutting into plant tissue, Tubulifera females deposit their eggs by pushing them into existing crevices, such as under bark, between flowers, or into leaf sheaths. Alternatively, they may glue their eggs directly onto the surfaces of leaves or bark. This evolutionary adaptation is reflected in their anatomy, as the terminal abdominal segment in Tubulifera is tubelike rather than split ventrally to accommodate an ovipositor.312