Nematodes are microscopic roundworms that occur naturally in soil, and certain species have been developed for use against specific garden pests. Rather than acting as a broad chemical treatment, each nematode species is matched to a particular pest, seeking it out and interrupting its lifecycle with far less impact on the rest of the garden than a chemical spray.
Sited well and left in peace, an insect house can become a genuinely busy part of the garden. Many gardeners start by comparing a few insect houses before choosing one to match the space available.
Placement decides whether the house gets used at all. A fixed position at around waist to head height, facing south or south-east to catch the morning sun, and sheltered from driving rain and strong wind, gives insects the stable conditions they need. Once occupied, the house is best left undisturbed through the nesting and overwintering period.
Not every beneficial garden insect lives in a hive or a colony. Many UK bee species are solitary, nesting alone or in loose aggregations, and insects such as lacewings and ladybirds shelter individually or in small clusters, particularly over winter. An insect house gives these species something a tidy garden often lacks: safe, undisturbed nesting and overwintering space.
Fish are worth thinking through carefully. Ornamental fish will happily eat frogspawn and tadpoles, so a pond wildlife equipment intended mainly for amphibians is usually better left fish-free. Leaving some leaf litter to settle at the bottom over autumn also gives amphibians a place to shelter through the colder months.
Hedgehogs typically hibernate through the coldest months, often in piles of leaves, log stacks, or purpose-built shelters tucked into a quiet corner. Anything resembling a bonfire pile should always be checked carefully before lighting, since it can look like an ideal hibernation spot to a hedgehog settling in for winter.