Wasps are our friends. They really are. Forget these buzzing pests hovering greedily round your jeely piece or drowning in your frothy pint,. I can still say that after swallowing one in a delicious slug of ale. These black and yellow-striped insects only briefly become pests once their duties in the Bike, or nest, are over. Then they’ve stopped pollinating our nectar-rich flowers and scouring the garden for the greenfly the Bike’s growing larvae need.

Many of us have come to hate and trap these wasps in jam jars to keep them off our food, but there are also solitary wasps that eat caterpillars and other creatures we call pests and have no interest in jam or beer. Crossocerus magacephalus nests in rotting wood and hunts bugs, aphids and caterpillars for its larvae while Ancistrocerus erietum nests in wall cavities and specialises in caterpillars. Also we mustn’t forget the little parasitoid wasps whose growing larvae consume many of our garden and greenhouse pests.

Adult wasps all need carbohydrates which sugars provide while the larvae crave a protein diet. While consuming protein from the tiny invertebrates worker wasps collect from our roses, their larvae secrete sugars after their protein diet and this in turn feeds the adults. So while a colony is growing, workers don’t look for the sweet treats on our plates. It is only at the beginning or end of the season when larvae aren’t around to supply sugars for them  that they may pester us.

When building up their energies, queen wasps pollinate flowers for nectar: I’m almost deafened by the sound of their busy buzzing round the loganberry in our greenhouse and always see lots round gooseberry and currant bushes.

So, although bumble and honey bees are the classic pollinators, wasps play an important part. In her excellent book ‘Endless Forms’, published last year,  Seirian Sumner notes that researchers in the U.S assessed the role played by different insects in pollinating buckwheat. They identified 5 different wasp species, honeybees, hoverflies and other flies and compiled a league table, counting the number of compatible pollen grains collected every minute. Honeybees topped the list but wasps were half way down, doing better than hoverflies. 

We rarely associate wasps with pest control. But how often do you see wasps in summer? Then they’re scooping up thousands of aphids, caterpillars and other ‘tasty’ protein-rich pests. I never see any green or black fly, thanks to their diligence.

Tiny parasitoid wasps also play a vital role. After adults have identified and laid eggs in their prey, the hatching larvae set about consuming their hosts. When laying eggs, the adults tweak their ovipositors to release a venom that numbs the host, making it a more compliant victim.

Many endoparasitoid wasps have developed a relationship with a virus which they inject into their prey. The virus prevents the caterpillar’s immune system from attacking wasp larvae and it alters the caterpillar’s saliva. This weakens the host’s immune system even more and induces it to grow faster, making a juicier meal for the wasp larva.

Plant of the week

Blackcurrant ‘Ben Connan’ produces quantities of delicious, large berries that ripen early. The plants are compact so do not need the very large space required by traditional varieties. They are not susceptible to mildew and are even resistant to Leaf Curling Midge.

The small, green flowers open early in the spring and are usually pollinated by queen wasps who appreciate the easily accessible nectar and are not seduced by showier blooms.