Clover cutworm Discestra (Mamestra) trifolii Hfn
It is ubiquitous throughout Bulgaria. It damages more than 40 species of plants, including vegetable and squash crops, fruit nurseries, apple, cherry, apricot, cotton, beet, tobacco, hemp, sunflower, corn, soybean, pea, alfalfa, clover, etc. The pupa overwinters in the soil. Imagoes fly from April to October and develop 3 generations.
Eggs are laid on the leaves of beets, corn, sunflowers, peas, etc.
Eggs are laid singly, rarely in groups of 2 to 20. A female lays 100–200 eggs. First generation develops on weeds. The second generation migrates on cultivated plants where they damage flower buds, flowers, cans of flax, cotton, tobacco, etc. pupating in the soil.
Monitoring with pheromone traps. The parameters and timing of trichogramma displacement is as for alfalfa nightshade. The same applies to displacement in capsules.
Peculiarities of pest control. The first generation develops on the weeds, on the periphery of the blocks, where the caterpillars feed. For this reason, the first trichogramma seeding should be done on the periphery of the blocks, including the weeds. Subsequent displacements on cultivated plants take place twice during the egg — laying period of the second generation and the third generation. As with alfalfa and other bollworms, accounting for the trichogramma efficiency zones by the hydrothermal coefficient (0.9–1 optimal HTC), and 0.5–0.8 or 1.3–1.7 results in a 30–40% increase in the norm and 1–2 more displacements.