Biology

The moth , Lepidoptera, pass through four stages of development: egg, larva or caterpillar, nymph or chrysalis, and butterfly (Figure 1).

• Forms of conservation and / or alternative hosts

Most of these butterflies hibernate through pupae, or even larvae, although other stages of development may aid in the winter conservation of these insects. They can be hosted by many cultivated and non-cultivated hosts.

• Stages of development

The eggs (figure 7-1), transparent, white, black-brown, mauve, etc., with a diameter of less than a millimeter, are deposited singly or in groups on the surfaces of leaves or various supports (figure 2). Subsequently, they hatch and give birth to caterpillars (figure 7-2) measuring 25 to 50 mm depending on the species, equipped with powerful mandibles that allow them to constantly consume plants, especially leaves (figures 3 and 4).

These caterpillars, of variable color (green, sometimes becoming brown to reddish with age), moult several times, before pupation or pupae. The pupae (Figure 7-3), which measure from 2 to 2.8 cm and on which we can clearly see the sheaths of the legs and wings as well as the abdominal segmentation, are reddish-brown in color. The adults (figure 7-4) are butterflies with 2 pairs of wings and whose wingspan varies from 25 to 45 mm for the species of interest to us. The fore and hind wings present a variable coloring according to the species (reddish brown, brown, gray), as well as more or less characteristic patterns (figure 5).

The duration of their cycle varies depending on the temperature, from ten days to several weeks. The caterpillars are mobile and move easily from one leaflet to another like the adults who do so more easily. We should add that the reduction in soil disinfection practices seems to be contributing to the resurgence of this pest, on vegetable crops among others.