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Clinical case: Colony losses from starvation in spring

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As the saying goes, “a practical example is worth a thousand words.” With this in mind, we have begun collaborating with veterinarians to share clinical cases they’ve encountered during visits to apiaries. As you will see in this second clinical case, Dr. Juan Molina will share an instance from Spain involving significant hive losses due to a lack of resources.

1. History, reason for the visit

In early May, a beekeeper from Galicia (Northern Spain) reported numerous bee deaths across his hives, including entire hives, at two separate mountain apiaries located kilometers apart to the Veterinary inspector of the Association. Despite unfavorable weather conditions, he arranged to visit the farm within 72 hours. The beekeeper suspected hive poisoning, particularly in hives with the highest bee populations, due to a settlement dispute.

2. Apiary history

The apiary is situated in a gentle mountainous area, surrounded by eucalyptus trees, potato plantations, fallow fields, low shrubs, and rapeseed fields that have yet to bloom. Although vegetation is lush, there’s a scarcity of flowers and numerous puddles. Protected from prevailing northwest winds, the apiary faces challenges with flooding channels, which can make access difficult during heavy rains.


During the visit, they managed to cross one stream, while the second stream had been restored by municipal machinery. The region experiences high humidity, especially during rainy winter and spring seasons, with rainfall 19% above average over the past five months according to the Spanish Meteorological Institute.


Since mid-February, the beekeeper has been providing stimulating feeding, offering 1000 mL (33.8 ounces) of homemade sucrose syrup infused with a 3 ml (0.10 ounces) vitamin complex per hive twice a month in interlayer feeders.


The last varroa treatment, using amitraz strips, was administered in November.

During early spring visits, the beekeeper removed severely depopulated and dead hives. The most recent visit in early April didn’t observe varroa, although parasitization on nurse bees wasn’t assessed. The beekeeper notes that many queens were one year old, as were created from blind nuclei in the previous season, with the hives remaining in the same apiary throughout the year (stationary apiary). Feeders that were already empty, were removed.


The Langstroth type boxes lacked rises and generally exhibited signs of aging, suggesting they could benefit from proper maintenance and protection with natural oils. Positioned on cement bricks about 25 cm (9.8 inches) above the ground, they’re accompanied by other small, self-sufficient apiaries near orchards and homes. Despite no signs of predation or Vespa velutina attacks, activity at the apiary was minimal due to the cool, rainy weather. There were no diarrhea spots in hives.

3. Hive inspection

Hive inspection revealed moderate mortality among drones and larvae, with some showing missing body parts. While no ants are present around the corpses, the lack of activity at the hive entrance prompts further investigation. Upon opening the boxes, dead bees with heads inside cells, capped brood with holey opercula, and cannibalized pupae inside cells are observed.

Although the queen was present, recent egg laying wasn’t evident. Frames lacked weight and pollen or honey halos, with side frames containing hardened capped honey from the previous year. The bottom of the hive harbored dead larvae, body remnants, and wax sawdust, with no signs of moth infestations. Empty cells revealed no scales or mummified larvae, nor was there a putrid smell.

Despite collapsed hives showing no signs of looting, overall apiary activity was low. Live bees exhibited malnourished appearance, with abdomens so shortened that the wings exceed the limit of the abdomen. Brood had a very dry appearance, with a lack of royal jelly.

Clinical case: Colony losses from starvation in spring
Starvation signs of honey bees

4. Samples

A small sample of live bees was taken for the laboratory. No samples were taken from dead bees because the time lag between death and testing makes nucleic acid detection difficult.

Differential diagnosis included:

  • Death from starvation and cold
  • Pesticide poisoning
  • Viral infections such as (ABPV and CBPV)
  • Nosemosis A or C

Samples taken for laboratory testing, including optical microscopy for Nosema spp., yielded negative results for microsporidia, with a low infection rate insufficient to explain mortality. Total protein (vitellogenin) determination in hemolymph wasn’t routinely offered by the laboratory.

5. Diagnosis

Starvation was discussed with the beekeeper, who acknowledged difficulty accessing the apiary due to a broken stream crossing. The beekeeper had hoped rapeseed flowering would replenish hive reserves, but unexpected heavy rain compromised this plan.

6. Treatment

The beekeeper was advised to immediately provide solid caloric food to prevent cold-induced deaths. Restimulation was discouraged due to depleted bee reserves. Offering pollen-based protein pills or alternative 10% protein patties we recommended as emergency measures to sustain hives until nectar and pollen supplies were available. It is always crucial to assess apiary suitability if access issues persist.

Pollen input should be monitored, ensuring diverse pollen sources1 and providing supplementary protein if necessary. It is also important to emphasize the risk of hive dependence on supplemental feeding and stress the need for continuous supplementation during flower failure or adverse weather.

Stimulant feeding should be gradual, ideally 500 ml (16.9 ounces) per week, with subsequent pollen or protein supplementation. The beekeeper should stay informed about weather forecasts and crop varieties to anticipate shortages. Varroa monitoring and pest control measures are essential throughout the campaign.

7. Follow-up

A telephone follow-up revealed the beekeeper’s decision to keep hives in place, anticipating rapeseed flowering despite delays caused by cold and lack of light.

8. Discussion, conclusions

Starvation, while more common in winter, remains a risk in spring due to fluctuating conditions. The Galician region, known for its annual 1,200 mm rainfall (47,24 inches), experienced a milder, wetter winter in 2023-2024.

Neglecting hive nutrition underscores the beekeeper’s responsibility for colony health and economic consequences of negligence. Anticipating and managing nutritional needs is essential for apiary health and success.

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1 At least 15 or 20 bees with corbicular pollen per minute at midday, with the hive at maximum activity. At least 4-5 different colors of pollen. If there is only one predominant color, it will be advisable to make a complementary contribution based on a protein patty.


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