As many of you will know I am as fascinated by the insects in my garden as I am by the flowers, if not more. I’ve spent 30 years observing all sorts of visitors to the garden and I’m especially interested in bees and wasps. But my efforts are as nothing compared to Jennifer Owen who gardens in Leicester. She is an entomologist and ecologist who specialises in hoverflies and she has studied her suburban garden seriously and scientifically for 30 years. She began in 1972 and in 1991 she wrote a landmark book The Ecology of a Garden — the first fifteen years. It sits on my bookshelf and I have delved into it often, but it’s a hard read for a mere gardener/observer.

The RHS have just published a much more readable and accessible book entitled Wildlife of a Garden — a thirty year study (£30). It’s well-illustrated and the information is arranged in an easy format, although it isn’t dumbed down. It should be on every gardener’s shelf because it contains detailed data showing the value of gardens in conserving wildlife. Inevitably, her conclusions and results have evolved since the first book was published almost 20 years ago, so this is a valuable book even if you have the first one.

When I spoke to Jennifer she explained that she “had spent nine years in Africa and observed the wildlife in her garden there and realised how important it was”. When she moved to Leicester, she set up special Malaise traps, tent-like mesh structures that trap flying insects into a collecting jar. She also trapped beetles and other insects found at ground level in pits. Her finds were sorted into groups, but many specialist entomologists helped her to identify them.

In all, she recorded 2,673 species, ranging from plants to mammals. She monitored moths, butterflies, beetles and hoverflies (among others) “in a very ordinary garden setting”, to use her words.

She found 533 species of parasitic wasp (Ichneumonidae) within the garden and six of these had never been described before. Many of these tiny creatures lay eggs in butterfly, moth, sawfly and wood-boring beetle larvae, among other things.

They develop inside their hosts and are commonly known as parasitoids because they actually kill their hosts. There are 2,028 recorded species in Britain and (between 1972 and 1974) 504 species were identified in her garden.

Sadly one of the conclusions Jennifer comes to is that “the abundance of insects has fallen off sharply in the last 30 years”. This has had a knock-on effect on wildlife. Starlings and house sparrows (once so abundant) have been casualties. Both are thought to have been affected by the shortage of insects. But Jennifer is confident that changes in agricultural management —wildlife strips for instance — will see these creatures return in numbers. She is not pessimistic.

“The outlook is reasonably good” she assured me. Some creatures (beetles and solitary wasps) have even “taken off in the last 30 years possibly due to climate change”, she explained.

Her message is clear. Every garden is a refuge where insect life abounds in great variety, some of it probably unknown to science. The fact that her garden is in suburban Leicester means that most gardens could attract a lot of mini-beasts. Your garden does not need insecticides; there’s an army of helpers out there ready and willing.