Dead Bees In The Yard - What's the cause?

Above: Swarm of dead honey bees - photograph sent in by Teresa Taramasso of Amarillo, Texas.

I sometimes receive emails from people who are alarmed to find lots of dead bees in the yard.  There can be perfectly natural (if unfortunate) reasons for this, or the reason can be pesticide poisoning.  I have quite a lot of information about poisoning by neonicotinoids - for example, here.

Honey Bees Sometimes Have A 'Clear Out' And Sometimes They Get Caught Out By The Weather

You may see dead honey bees when the colony is having a clear out, removing dead bees.  

On the other hand, you may see quite a lot of dead honey bees around a hive or in the yard in winter, when the temperature fluctuates, or following a long cold period and possibly snow. 

What happens is that on a day when the temperature has warmed slightly (perhaps the sun is shining) honey bees will take the opportunity to remove dead bees that have accumulated over a period, from the hive (the bees may have died for natural reasons, such as old age).  

The removing of these dead bees is important in order to preserve hygiene, and although it will seem like many, many bees to you, you have to remember that a colony of bees has thousands of individuals.  In addition to this, honey bees may need to take cleansing flights (which means they need to leave the hive to defecate). 

Severe Weather

Honey bees may also be encouraged by warm sunshine to take a cleansing flight, only to be caught out by the weather, resulting in people seeing dead honey bees. 

In addition to this, bees can die during winter due to starvation – the inability to get out and forage, inability to access the food stores, or insufficient food stores in the hive.  Where a beekeeper is involved, hopefully he or she will be able to prevent this happening by supplying additional food for the bees. 

Diseases can also take their toll on bees.

What If It's None Of The Above?

If you find many dead honey bees, and you have not had a very recent cold spell, then it may be poisoning.  I recommend you photograph the bees, and contact your local council to ask whether they have been spraying, or consider whether it is possible a local farmer has been spraying their crops.

I also think it would be a good idea to notify your local beekeeping association.  They may already have information, or may appreciate a warning.

Some countries also have notification schemes whereby inspectors can be informed (ask your local beekeeping association whether this is the case).  In such cases, bees can be sent off for testing for pesticide poisoning.  If such a scheme exists in your country, gather plenty of samples, give some to the inspector, and retain some (I have heard of samples ‘going missing’!).

A sad case....

I was sent some photographs of lots of dead honey bees by Teresa Taramasso of Amarillo, Texas (below). 

Below is the situation described by Teresa, who found lots of dead bees in her yard, and I thank her for permission to use her emails and photographs:

“A couple of weeks ago we had a large swarm of bees appear in our back yard, 90% of them were swarming around my asparagus plants. They seemed disoriented, then by the end of the day they disappeared. Today I found out why….they all died.

In looking at a pile of what I thought was just garden dirt I realized that is was bees, hundreds of them.

What would cause this? I have left them where they died just in case someone wants them.

We’d had a storm blow through from the north but nothing out of the ordinary.  The swarm appeared in my yard and from where I have no idea. I live in a housing track that is about 4 years old…… no large trees around that would hold such a group.  If they were living in the ground they could have been disturbed by construction about three blocks up from us.  I was just shocked to see a swarm that didn't seem to have a purpose of settling to a new home.  I don't use sprays so they must have gotten hit from somewhere nearby, just don't know where they could have flown from or how far they came.  Our last freeze was a couple of weeks ago but they appeared just before that I believe (we had a late season snow).  Very sad indeed.   At first I thought the swarm was made up of thousands of gnats which can come out but as I looked closer I realized that it was bees.

You can read more about finding dead bees here.

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