Let's fight the American Caterpillar
This moth (Arctiidae fam.) Is a species of North American origin (United States, Canada), was introduced in Europe in 1940 and in Italy between 1975 and 1977. Starting from the Val Padana, it spread rapidly throughout Northern and central Italy, by means of transport, causing serious damage to the deciduous trees present in urban green areas, along roads and railway lines.
Adult: candid white butterfly or dotted with black (typical shape). Wingspan 25-30 mm; filiform antennae in females and combed in males;
Eggs: pale green in color, they are laid together in plates glued mostly on the underside of the leaves;
Larva: yellowish-brown in color with black head and gray dorsal region, covered with long white and black hairs. At maturity it reaches the length of 30-35 cm;
Chrysalis: shiny brown, it has the terminal part (cremaster) provided with thorns, with a flattened apex. It forms inside a cocoon of sparse silken threads.
The newborn larvae first erode one of the leaf surfaces and then, once grown, they eat the entire leaf of which only the main veins remain. They can attack about 200 species, with a clear prevalence for tree and shrub deciduous trees.
Among those that are used in street and park trees we can mention: mulberry, maple, plane trees, lime trees, elms, horse chestnuts, ash trees, poplars, willows etc. (never the conifers). Among the plants of agricultural interest there are several fruit trees: apple, pear, walnut, plum, vine.
Natural enemies are represented by predators, parasitoids and pathogenic microorganisms. Recent studies highlight how these factors play an important role in limiting pest infestation (Marchesini et al., 1997). Among the predators, different species of spiders and insects have been observed such as the chrysopa, the scissors and the wasps. Even the birds can perform an effective containment action. Among the pathogenic microorganisms isolated, particularly active on the wintering chrysalis, are entomopathogenic fungi.
American Caterpillar, Iphantria: Various methods of struggle
cut and burn the whitish serice nests as soon as the larvae have started their trophic activity. This operation must be carried out starting from the middle of May for the first generation larvae and repeated in the middle of August for those of the second generation;
for treatments in public environments we recommend the use of BACILLUS THURINGIENSIS (var. KURSTAKI) taking into account that:
· It is a product with low toxicity and respects useful insects;
· It acts by ingestion, it must therefore be used when the larvae are still young and begin to eat voraciously the vegetation (about 20 days after the hatching of the eggs);
· It is sensitive to sunlight, so it is preferable to distribute it at dusk;
· The indicated doses vary from 100 to 300 g / hl depending on the stage of development of the larvae. It is important to wet the vegetation well (10-15 liters of suspension per plant depending on the size).
the following active ingredients can be used with good results: natural pyrethrins, diflubenzuron, tebufenzide, feflubenzuron, synthetic pyrethroids.
Sex pheromone traps represent a valid tool to detect the progress of flights and identify the most appropriate time to intervene.