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Do Polar BearsGet Lonely?

THE LAST WORD

Brolly life

When I took the cover off my picnic

table’s sun umbrella, I found a

number of these structures

running down one of the folds (see

top photo). They look like they are

made of dried mud and inside each

one is a vivid yellow powder and a

single thin, curled-up larva. Each

structure was about 5 centimetres

long. What did it, how did it do it,

how long did it take – and should I

get rid of them?

■ This is a nest created by the female red mason bee, Osmia rufa, for her young. These are solitary bees and the female works alone from March to June building the nest one cell at a time. In each cell she lays an egg and stores a supply of pollen. The larva will hatch, eat the pollen and overwinter in a cocoon before hatching into an adult.

Red mason bees usually nest in hollow stems, beetle borings and cracks in walls. They are excellent pollinators and are very safe around pets and children. The sting is tiny compared to a wasp’s or a bumblebee’s and it is not used at all unless the bee is roughly handled. I would recommend that you do not touch the nest or move it very gently.

Special nests for solitary bees can be bought in shops which, if placed close to the original nest, should stop them from settling in your furniture.Fiona LambertBristol, UK

■ The structure is a nest of the red mason bee, or Osmia rufa. This spring-flying species is solitary – each nest is the work of a single female. The insect is called a mason bee because it builds walls of mud to partition its cells and to seal the nest, unlike other species which use a mastic of chewed leaves or resin as a building material. The photo shows 14 cells, and the yellow powder is the pollen store on which the larvae feed.

I attach a photo (bottom) of an O. rufa female at artificial nests in my Leicestershire garden.

These useful bees are easy to attract with artificial nests such as cut lengths of bamboo with an internal diameter of about 8 millimetres. Females are adept at finding suitable cavities – I have

found nests in old shed locks.Species of Osmia have great

potential as alternatives to the honeybee as managed pollinators of spring-flowering orchard

crops. O. rufa is used for apple pollination in parts of Europe and its relative, Osmia cornifrons, pollinates apple orchards in Japan, where about 60 per cent of all apples are pollinated by this species.

I am involved in further development of the use of the American blue orchard bee, Osmia lignaria, as a managed pollinator of almonds in California.Chris O’Toole,Honorary Research AssociateHope Entomological CollectionsOxford University Museum of Natural History, UK

THIS WEEK’S QUESTIONS

HIDEY HOLE

With climate change, earthquakes, volcanic eruptions and other natural disasters to contend with, where on the planet is the safest place to live?Michael LeonardStoke-on-Trent, Staffordshire, UK

PRETTY IN PINK

Why are girls, and particularly young girls, drawn to the colour pink? Is it something society has instilled in them? Or is there something attractive about the colour itself? Shops seem to be full of pink clothes for young girls – are they reacting to demand or just forcing their designs upon children who would not otherwise choose this colour?Anna GarrardLondon, UK

Last words past and present, plus questions, at www.last-word.com

“The larva will hatch, eat the pollen and overwinter in a cocoon before hatching into an adult”