Another girdled snail

I spotted this Girdled Snail, Hygromia cinctella, the second ever I have seen, climbing up a wall in my street a couple of days ago. The white whashed wall made a white background for it and I was pleased to get to photograph the live snail as it went about its business.

A bumper year for 7 spot parasites?

In the last few days I have found quite a few 7 spot ladybirds parasitized by the wasp Dinocampus coccinellae in the garden: live ladybirds snared to a silky cocoon underneath them. Today I did a quick count and found eight. You can see their portraits on this post. This is being a successful year for 7 spots: there are so many around it is hard not to get one or two ladybirds in the background of any bug photo I take! It is no surprise that ladybird parasites are enjoying this ladybird bonanza. If you want to find out more about the rather gruesome Dinocampus life cycle click here.

One on sage

on the conservatory frame

a second one on the spurge

one under a Lamb's Ears leaf

An odd one, with the cocoon on one side on a bougainvillea leaf in the conservatory

one on an orchid in the conservatory

a second one on sage

Dinner of the green bug muncher

After the very rainy April we are having a teasel growing in the garden is looking very luscious. It has grown a large rosette of leaves, and developed two large leaf-cups which are filled with water to the rim. If you want an account on this fascinating carnivorous plant, check here. I had a peek a couple of days ago to check if any drowned invertebrates were visible. And there were indeed! On the bottom cup (above) a 7 spot floated on a very cloudy liquid, while on the top one, a drowned slug was visible at the bottom of the clearer water, and a few small unidentified insects. What a catch!

The end of the affair

As the solitary bee herald of spring, Anthophora plumipes, is my favourite bee. It is with some sadness I found this dead male on the path today. The rain might have contributed to its demise, but it might also have reached the end of its natural life. In my patch, the first males appear at the beginning of March, and the last males, usually worn individuals, fly until the middle of May, barely two months of male activity, but the lives of individual males are bound to be even shorter, something I was referring to in my last post. On the bright side, the females will be still busy nesting for another month

On the odd life cycle of bumblebees

I stopped by the comfrey patch this morning. The comfrey has now been in blossom for a good month. A Small White butterfly was feeding on comfrey, but I couldn't snap her. A ginger queen Bombus pascuorum fed on the blossom. A queen wasp got comfortable on a leaf and basked in the sun, as did some hoverflies. While I watched a couple of Anthophora plumipes males patrolling and feeding, a tiny worker of the tree bumblebee Bombus hypnorum, the first of the year, turned up (above). As I compared the sizes of these two bees – the bumblebee worker was smaller than A. plumipes - I reflected on the different life cycles of these two bee species. A. plumipes, a solitary bee, has males and females, while bumblebees, in addition of males and females (queens), have a worker caste. In bumblebees there are no males for most of the year: A male has a relatively short - if hectic - life. Upon emergence in the summer, he will find a queen and mate with her. The queen will store his sperm and use it to fertilise her eggs the following spring, when she will emerge from overwintering, build a nest and lay fertilised eggs, which will hatch into worker larvae. She will be busy collecting nectar and pollen from early flowering trees and plants to rear these larvae, and once the workers emerge, they will take over from the queen in collecting more nectar and pollen for subsequent eggs, although they won't reproduce themselves.  In the summer, the last batch of eggs of the queen will produce new queens and males, which the workers will help rear. Once they leave the nest, the founder queen and workers will die and the cycle starts again. Wasps, ants, bees, and bumblebees (hymenopterans) share a weird way to determine the sex of the offspring: fertilised eggs become females and unfertilised eggs become males: a system called haplodiploidy.

  Most sexual organisms have two sets of chromosomes: a set they inherit from their mother and another that comes from their father, but as bumblebees and other hymenopterans do not have a dad they just have a single set of chromosomes, the set coming from their mother.

How strange is that? If you think about it, the system means that bumblebee males don’t have dads, they also cannot have sons, only daughters, although they can have grandsons and have granddads. In addition, this arrangement causes strange relationships between the family members. We are equally related to our parents than to our kids – on average – but due to haplodiploidy, bumblebee sisters are more strongly related than they are to their mums. This is because full sisters have received an identical set of chromosomes from their dad, in addition to the set they receive from their mum, which is a mixture from the sets the queen received from her parents.

 This unbalanced genetic relationship between mother-daughters and sisters is thought to underlay the evolution of the worker caste, which do not reproduce, but help their mother to rear their own sisters.

The solitary bee Anthophora plumipes

A wasp? No, the exquisite wasp mimic hoverfly Myothropa florea

This is the real wasp. A queen common wasp 

Hoverfly Syrphus ribesii 

Another basking fly

A queen Bombus pascuorum