Wasps of the genus Vespula are the common wasps that appear at hives in late summer. They are not hornets, and the problem they cause is of a different kind.

Why late summer

In that period their nests are at their largest and their own food source disappears. They switch to sugar — and a beehive is the richest sugar source around.

What they do

• Rob stores at the entrance
• Enter and empty weak colonies
• Take individual bees, mostly weakened ones
• Clear dead bees and debris in front of the hive

Unlike invasive hornets they do not hover and hunt at the entrance. The damage comes mainly from robbing, not predation.

When it becomes serious

A strong colony defends itself. Wasps only become a problem with:

• Weak colonies and nucs
• Colonies that have gone queenless
• An entrance left too wide
• An untidy apiary with spilt honey

Measures

• Reduce the entrance to a few bees wide — the most effective measure
• Unite weak colonies rather than letting them be besieged
• Clear up spilt honey and extraction waste
• Close the hive of a dead colony immediately
• Seal gaps between boxes

About traps

Sugar-baited traps also catch honey bees and beneficial insects. They do not replace reducing the entrance, and deployed broadly they do more harm than good.

Perspective

Wasps have a role as scavengers and as predators of pest insects. They rank low among the causes of colony loss; check Varroa, nutrition and wintering first.