Nosema spores (indicated by red arrows) under phase contrast microscope.

Hypothetical natural distribution of Apis mellifera mellifera.
In comparison to other subspecies A. m. mellifera is better adapted to low temperatures Adaptations of honeybees Apis mellifera mellifera L. and Apis mellifera carpathica to low winter temperatures,
Russian Journal of Ecology
, Volume 43, Number 5, p.409–411, (2012)
[1].

Ventral view of left mandible of honey bee queen (A), worker (B) and drone (C). After Snodgrass (1956, fig. 23) Anatomy of the honey bee,
, Ithaca, p.334, (1956)
[2].
From evolutionary point of view the mandibles are homologous with coxae of mandibular (forth) head segment.

Internal anatomy of first instar of honey bee larva (blue - digestive system, green - silk gland, red - nervous system). After Schnetter (1994, fig. 26) Morphologische untersuchungen über das differenzierungszentrum in der embryonal-entwicklung der honigbiene,
Zeitschrift für Morphologie und Ökologie der Tiere
, Volume 29, Number 1, p.114–195, (1934)
[3].

Abbreviations:
Br - brain
Gng - ganglion
Ht - heart
Mal - Malpighian tubules
Ov - ovary
Proc - proctodaeum
skGld - silk glang
Sp - spiracle
Tra - trachea
Vent - ventriculus

Trophallaxis between two honey bee workers. The worker on the left is collecting food from the worker on the right.
The transmission of food between worker honeybees,
British Journal of Animal Behaviour
, Volume 5, p.41-47, (1957)
[4]The nature of trophallaxis in honeybees,
Insectes Sociaux
, Volume 29, p.209-221, (1982)
[5]

Mouthparts of honey bee worker (side view). After Goodman (2003, fig. 5-13) Form and function in the honey bee,
, Cardiff, p.220, (2003)
[6]. Most of the time the honey bee mouthparts are folded and hidden behind the head. Then bees can use their mandibles to manipulate solid substances. In order to collect liquid food bees need to unfold the mouthparts.

Development of honey bee queen. Numbers indicate day of development after egg laying.

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Small amount of pollen can be present in food of queens larvae Diversity in life history of queen and worker honey bees, Apis mellifera L.,
Journal of Asia-Pacific Entomology
, Volume 18, p.145–149, (2015)
[7].

Female of Varroa (markerd red) entering a brood cell.

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When a worker infested with Varroa approaches brood cell just before capping, the mite leaves the worker and goes to the cell rim or capping of the nearby cell. Next the mite enters the cell and hides behind the larva at the cell bottom. This takes about one minute Behaviour of Varroa mites invading honey bee brood cells,
Experimental and Applied Acarology
, Volume 18, Number 6, p.371–379, (1994)
[8].

Female of Varroa destructor, front view. (scale bar = 0.5 mm)

Reproductive system of honey bee drone.

Blb - bulb of penis
Dej - ductus ejaculatorius
fbl - fimbriated lobe of penis
MGld - mucus gland
Tes - testis
Vd - vas deferens
Vsm - vesicula seminalis