The sun has been shining, temperatures are soaring and flowers are blooming. So it is inevitable that along comes a fly in the ointment. And these little flies are thrips.
Thrips are common little insects (most are about 2mm long and slim) and affect a wide range of plants. They are sap suckers and as they suck the plant cells dry these turn silvery or bronzed so affected leaves are speckled or discoloured. Some are native while others, such as the Western flower thrip from America (reaching the UK in 1986) are serious, introduced pests. In the ‘wild’ they affect a wide range of plants but in rural areas they usually only become obvious when wheat and other grain crops reach maturity or are harvested and the thrips leave their previous ‘home’ and masses move into gardens. They are also commonly called thunder flies because they are most obvious in hot weather and often fly in huge clouds in stormy weather – they may be affected by electrical charges during storms.
They tend to like pale flowers and I have had pale daylily flowers covered in them. In addition they like to crawl into crevices – apparently this is their way to avoid being killed by huge rain drops – and they get under your clothes and, in the house, can get into electrical equipment. I had a computer monitor ruined by one that looked like a comma – a notable premonition of the Jonathan Creek episode ‘The Seer of the Sands’ – and also in a camera viewfinder.
On flowers they suck the sap and bleach the petals of colour. You can kill thrips with insecticides, if necessary, but you can’t spray open flowers because of the threat to pollinators.
But the sweet peas are still growing well and flowering away. I just can’t pick them for the house. In practice, I could if I pick them and put them in water and put them in a shed. Like pollen beetles the thrips will leave the flowers and fly to the window. The next day they (the flowers) can be brought into the house.