Nonetheless, indiscriminate spraying with insecticides is not the answer. Pollinators such as bees, beetles and butterflies are so crucial to our ecosystems that we cannot survive without them. Others, natural predators such as dragonflies, lacewings, praying mantids and ladybirds already prey on the bad guys. Pollinators and predators alike are beneficial both to the environment and to humans.
The bad guys are mostly vegetarians that devour our precious shoots and foliage, but the ones that get the worst press are those that bite or sting humans and can transmit diseases. In this regard, our number one enemy is the mosquito, which has acquired extra menace in Thailand because one species, aedes aegypti, a large striped species, is the vector of dengue fever. Figures have risen sharply; in the country at large, there were more than 46,000 cases in 2022. Almost certainly, this increase is related to excessive rainfall and the existence of casual puddles of water favoured for breeding purposes by aedes. Oddly, malaria, which kills more than 600,000 people each year, is virtually unknown in the kingdom.
But even mosquito or midge bites are unpleasant enough, the more so if you are allergic to them. The female mosquito is the blood sucker, (the male feeds harmlessly on pollen) needing the transfusion to provide sustenance for eggs which she will later deposit in water. Having pierced the host’s skin with her sharp proboscis, she injects an anticoagulant saliva which allows the blood to flow more easily. It is this fluid which dilates our capillaries, and causes both the swelling and subsequent irritation.
As gardeners we can take precautions. Ensure that any standing water (e.g. fish or lily ponds, or lotus vases), actually contain fish. Even small varieties such as guppies or sword tails will immediately gobble up any eggs or larvae. Other natural predators include insect-eating birds and large insects such as dragonflies, spiders and praying mantids. I used to have an infestation of Oleander hawk-moth caterpillars which devoured all the foliage on my tabernaemontanas. A local coucal discovered this abundant and succulent harvest. End of story ‒ at least for the caterpillars…
Try to avoid gardening in the early morning or before sunset when ‘mozzies’ are on the prowl, and avoid areas of deep shade and lush vegetation. Wear a repellent on exposed skin: Veet is effective for several hours and though less potent, natural products based, for example, on citronella, eucalyptus oil or neem, are a useful deterrent. Enclose feet and ankles: the levels of CO2 which attract the insects are higher in these areas of the body. Mosquitoes know all about smelly feet. Also, encourage their natural enemies – birds, skinks and lizards.
If mosquitoes are enemy number one for the gardener, others can prove equally ‒ well – irritating. Take ants. They are ubiquitous, having colonised every part of the globe bar Antarctica. Here in the tropics, they can certainly bite and sting, especially the aggressive weaver ants that create leaf nests in trees, or the large black ants that breed underground or in saucers at the base of flower pots. They characteristically spray formic acid; after a massed attack by red ants, one can smell the acid on one’s skin.
What makes ants more of a problem than they are, unlike mosquitoes, social creatures with colonies which they protect so effectively that they have few natural enemies. Even spiders will not venture near these fortresses manned by soldier ants. But their principal nuisance for the gardener is their capacity to forge relationships with other creatures such as aphids and mealy-bugs. These tiny insects feed destructively on plant sap and produce a sweet substance called honeydew which is ‘milked’ by the ants. In return the ants offer a symbiotic relationship whereby these sap-suckers are protected from predators such as ladybirds. Plants weakened by such attacks often develop fungal diseases or die.
Oddly, neither mosquitoes nor ants are top of the most feared or hated insect list. That dubious honour goes to the spider. True, there are many venomous species of spiders, especially in Australia. And in the kingdom, black tarantulas and brown widows carry a nasty bite. But on balance, they are the gardener’s ally, consuming mosquitoes and flies which are ensnared by their webs. Useful bio-controls…
Nonetheless, it has been estimated that up to 50% of women are arachnophobic. Fear of spiders runs deep…
Patrick Campbell’s book ‘The Tropic Gardener’, described in one Bangkok review as the best book on Thai gardening for 50 years, is available for B500 (half price) to personal callers from 59/84 Soi Saiyuan 13 in Rawai (Tel: 076-613227 or 085-7827551).