Curious Bee-Fly Behavior

[Lester]

The Bee-Fly is vibrating the rear of its abdomen in dry sheltered soil. Seems to be vibrating lumps of soil.

The one on vegetation has a soil lump stuck to its rear!

What is this behavior?

Ovipositing???? (reminded me of how wasps seal a burrow but vibrating their mandible)

It was warm and sunny (today) so they are not vibrating muscle for warmth. There were several at this in more or less the same place.

Here is a 3 frame animated gif to give you an idea



the one on vegitation



and a couple of stills

[snowdrop]

Curious. Would love to hear an explanation about this.

[eucera]

I'll have a go! This is behaviour I have seen many times with B. major and also B. minor.

The insects you are seeing are females. Bombyliid eggs are sticky and the female is scooping up fine dust particles, which coat (and thereby weight) the eggs. When the female is hovering over a bee burrow in the ground, she will flick her abdomen downwards, ejecting the weighted eggs towards their target - the open mouth of a mining-bee burrow.

the Bombyliids appear not to be all that fussy, but flick eggs at virtually any available burrows!

Voila!

[Lester]

Thanks eucera, so my guess of Ovipositing is right.

[eucera]

Well... not quite. This is pre-oviposition behavior. oviposition is done in flight and is a bit of a scatter-gun effort really

[Lester]

Originally Posted by eucera

Well... not quite. This is pre-oviposition behavior. oviposition is done in flight and is a bit of a scatter-gun effort really

My field guide (Chinery) notes the larvae live as parasites of mining bee larvae. I had the idea they actually directed the eggs to the burrow, but clearly not.

So with the one flying over vegetation with the earthy egg mass, is that just normal foraging or scattering eggs?

[snowdrop]

A very learned and interesting answer eucera. Thanks.

[squishy]

brilliant things bee flys

i got an opportunity to photograph the larval case of one a few weeks ago.