## 1 Introduction  
Early spring in central Europe coincides with unfavorable conditions for the spring development of honeybee colonies. Usually, there are alternating cool and warm periods, with cool days predominating. Spring cold snaps have been correlated with interruptions in flight activity, reduced pollen intake, and increased brood cannibalism, resulting in the reduction in nurse populations that then have to carry heavier nursing loads [1]. Under such conditions, spring development depends on environmental factors outside the colony, such as temperature and the availability of fresh pollen [2, 3]. However, the factors of a bee colony nest environment, such as the strength of the colony or the quality of nursing bees, are equally important [4]. Another crucial and still poorly elucidated factor is the bee comb as an element of the environment of the bee's nest [5].  
The identification of honeybee subspecies relies on the exhibition of distinctive morphometric traits which are highly heritable and are therefore a good identification tool [6]. However, the value of these traits undergoes seasonal fluctuations associated with larval nutrition, as demonstrated by [6, 7]. This opinion has been confirmed by [PERSON] et al. [8], who found that worker bees that had emerged from more poorly noruished larvae had a lower body weight and a smaller surface area of the first pair of wings than those emerging from optimally nourished larvae. In turn, [PERSON] [9] found that workers that had developed from malnourished larvae had a shorter probocsis and shorter first-pair wings. Due to seasonal changes in the body size, worker bees should be sampled for morphometric analysis in summer months when they are larger [6, 7]. They should not be reared in very dark combs, as the size of the worker bee also depends on the size of the cell [6].  
A study conducted in South America by [PERSON] et al. [10] on colonies with nest combs built without the use of a wax foundation showed a considerable variation in the width of comb cells, ranging from 4.17 to 8.07 mm even in the same colony. At present, the width of standard cells is usually in the range of 5.40-5.50 mm. The width of worker comb cells in natural nests of the European dark bee (_Apis mellifera mellifera_) was reported to range between 4.90 and 5.10 mm [11]. Currently, 4.90 mm wide comb cells are referred to as \"small cells\" [11; 12; 13].  
It was expected that an increase in the width of comb cells via the use of an artificially produced wax foundation would result in a proportional increase in the worker body size [11] and, consequently, in an increase in the honey yield of colonies. The belief that the worker body size changes proportionally to changes in the cell width still prevails [6; 7; 11]. However, it has been shown that keeping bee colonies on small-cell combs exerts a significant effect on the morphological traits and the biology of worker bees. [PERSON] and [PERSON] [11] found that a 7-8% reduction in the comb cell width resulted in a mere 1% decrease in the width of the worker head and thorax. Similar results were reported by [PERSON] and [PERSON] [14]. Our previous work also supports these findings, indicating that the rearing of workers in small-cell combs in the colony kept on standard-cell combs resulted in an increase in the value of the fill factor (thorax width to cell width ratio) [15]. Additionally, it contributes to a higher effectiveness of hygienic behavior [16; 17] and a higher rate of springtime colony development [18] as well as an extension of the lifespan of workers [19] and has an impact on the activities of the proteolytic and antioxidant system in the hemolymph of workers [20; 21].  
Therefore, the aim of this study was to find out whether small-cell combs provide as favorable conditions for rearing worker bees as standard-cell combs during the spring development, expressed as a lack of statistically significant changes in morphological traits.