You probably didn't think you'd find the common dust mite in our roundup of dangerous insects but when it comes to Britain's deadliest bugs, these tiny invertebrates that can only be seen under a microscope are the biggest killers. 90 per cent of asthma sufferers in the UK identify dust times as a trigger for their attacks and charity Asthma UK says there were 1,143 deaths from asthma in the Britain in 2010. While not all of these deaths were caused by dust mites, droppings left by the insects can trigger asthma attacks.