A new and potentially strong outbreak of the European spruce bark beetle Ips typographus has begun in the Leningrad region in 2021. The permanent presence of a signi cant quantity of the species in the spruce forests of the Karelian Isthmus (Leningrad Province) created a basis for a rapid increase of the abundance of this species. The development of a breeding outbreak was provoked by a sharp increasing in temperature in June-July 2021. Due to the increase in temperature, two sister and two main generations successfully developed. The mass appearance of two generations of the European spruce bark beetle in the forests of the Karelian Isthmus was revealed for the rst time. A part of the population, approximately 56% of individuals, developed according to the bivoltine type (two generations), while the rest developed according to the univoltine type (one generation). This feature of development provides the European spruce bark beetle with the resistance of populations to adverse weather conditions. The part of the second generation that started to develop earlier had a high reproduction energy (the ratio of the number of o spring beetles to the number of parent beetles - 4.7), close to the reproduction energy of the rst generation (6.0). The next group of the second generation, apparently, was mainly represented by the o spring of the sister generation. Development indicators in this group were signi cantly worse (reproduction energy - 1.3). A signi cant part of the individuals did not have time to complete development. The bark beetle stock (number of individuals per hectare), which ensures a rapid increase in the number of spruce bark beetle in the conditions of the Karelian Isthmus, can be estimated at 140- 150 thousand beetles per hectare (b/ha). In the case under consideration, the bark beetle stock was higher - 187 thousand b/ha, which ensured the appearance of o spring in the amount of about 3 million b/ha, i.e. a very large number capable of providing a rapidly growing outbreak. The rapid and steady trend of temperature growth and the presence of a large amount of food supply for the European spruce bark beetle in Leningrad Province and in the southwestern part of Karelia, and the preservation of the bark beetle stock suggest that this outbreak will develop rapidly, and in the near future we can expect its recurrence.