Insect Friends and Foes A Talk by Martin Harvey 20th April 2009

Martin Harvey is exceptionally knowledgeable about insects and other invertebrates. In this talk he informed us about the members from these groups of creatures which may be found in our gard ens .
Martin told us about some surveys which have been carried out in urban gardens to help discover the ecological importance of ordinary gardens. Jennifer Owen has surveyed her own suburban garden in the Leicester area. She does not use pesticides and grows nothing unusual.. She identified around 1700species in her garden. This included a third of Britain's butterfly species, a half of the hoverflies and 11% of the native plant species. In Sheffield another survey has looked at 60-70 gardens to try to understand the bio diversity that occurs in these areas.
Gardens are 1.8% of Britain's land area. They provide trees, ponds and nest boxes for our wildlife. Rural as well as urban gardens prove to significant in providing homes and food for a variety of creatures. Some rarities may be found in gardens. Purple Emperor butterflies have been seen in local gardens and Martin has recorded a rare weevil in his garden in Kimble. It appears in May, it has a long snout and has long orange legs. If seen, tell Martin please. Garden Tiger moths used to prosper in our gardens, feeding on dock and plantains but they have undergone a considerable decline.. Stag Beetles prosper in association with urban gardens breeding in dead wood which is in contact with the ground

Insect Friends
Some of our insect friends in the garden are those which help decompose dead vegetable and animal matter. The most easily identi f iable of these is the wood louse of which there are 8 different species. The Sheffield survey found that very small insects called Springtails were the most numerous and these are important during the final stages in the decomposition of vegetable matter.
All insects in the garden are important even if they are only part of the food chain. Of the herbivorous insects, caterpillars of moths and butterflies or shield bugs, few are a problem and they add to the diversity within our gardens and attract other creatures as well. Martin suggested that within most gardens it would be easy to see over a hundred moth species within a year.
There are further invertebrates which act as predators , maintaining an ecological balance within the garden keeping the herbivores in check.There are over 300 species of garden spiders many of them specialising in the type of prey they hunt. Ground beetle will eat the larvae and eggs of insects. Other predators will parasitise the caterpillars of insects by injecting their eggs into the them. Amongst these are the ichneumon wasps a large family of insects which are parasitic.
More friendly insects are those which pollinate plants when moving from one flower to another in order to feed. There are many of these, honey bees, bumble bees, moths, butterflies and even some beetles

Insect Foes
One of our insect enemies in the garden is the vine weevil, the larvae of which feed on plant roots. This specie has been introduced from abroad. There are species of hoverflies whose maggots will feed on bulbs , and wasps may be a dangerous pest if they nest in or close to the house.
The Harlequin Ladybird, an invasive migrant has become notorious in recent years. Although it eats aphids and greenfly, it will also eat the larvae of other species of ladybird as well as those of butterflies and moths threatening the existence of our native species. The Large White butterfly can be a pest in the vegetable garden, where its caterpillars will feast on all sorts of brassica.

Wildlife Gardening Tips
The provision of food and lodging within the garden is important. Long grass, decaying flowers, a mixture of trees and shrubs, piles of logs, ponds and compost heaps may all provide insects with sustenance. Some plants can be kept to benefit specific insects. Crucifers such as Garlic Mustard, Lady's Smock, and Honesty may provide the larvae of the Orange Tip butterfly with food, similarly Buckthorn will attract the Brimstone butterfly for the same reason. Martin referred to the Sheffield garden project again to say that insect numbers do not correlate to the size of the garden. The strength of the garden is its diversity. To help Martin gave us some tips. Do not keep the garden too tidy, do not dead head flowers immediately, grow a variety of trees and shrubs, do not use pesticides but squash pests instead and have a variety of habitats in the garden.
For more information on this subject, Martin referred to some books, these were :- "Garden Creepy Crawlies" by Michael Chinery, "Guide to Wildlife Gardening" by Richard Lewington and "No Nettles Required" and "An Ear to the Ground" by Ken Thompson. On the Butterfly Conservation website there is information about "Gardening for Butterflies". Martin also recommended the "Evolution Megalab" which has fascinating data about the Banded Snail.

Thanks to Martin for a captivating talk.