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Weather Watch: Bees and hoverflies thriving in warm and wet weather

A ringlet butterfly

A ringlet butterfly

  • by By Brendan Jones, Director of Forecasting at MetDesk in Wendover
 

Whilst for many, summer is one of our favourite seasons, a downside is the number of insects flying and crawling around.

Relatively warm summers such as 2014 seem to make the problem worse, but do insect levels really increase in hot summers?

Well, in some cases, but it’s not just the heat that allow insects to thrive.

Many also need rain to keep nectar levels high and to prevent their bodies drying out, so dry, hot summers actually often see a reduction in their population. More important is the weather in the preceding months.

In 2013, the very cold March and April, and then unsettled May, led to significant decreases in levels of bees, moths, butterflies and flying insects in general; this in turn leading to a reduction in the food available for many types of bird.

Not all insects were affected by the severe 2013 winter and spring however, with many lying dormant well beneath the ground, where temperatures stayed higher. Insects are in fact very resilient at coping with cold temperatures.

‘Freeze-avoidant’ insects can remain alive below 0C, as long as temperatures stay higher than the freezing point of their bodily fluids; this sometimes being as low as -20C.

Examples include pine beetles, aphids and ticks.

‘Freeze-tolerant’ insects are even more remarkable, some surviving when up to 60% of their bodily fluids have turned to ice; cockroaches, midges and caterpillars belong to this category.

Most crucial are weather conditions once spring properly starts and insect reproduction and egg-laying begin.

A sudden cold snap after this can devastate summer insect numbers.

Winter and spring 2014 were consistently warm, whilst the summer has continued to see mostly above average temperatures, but also plenty of heavy, thundery downpours.

Insect populations have therefore been quite high.

Bees and hoverflies are currently thriving, whilst red admiral butterflies are also doing well.

Rather cool and breezy in Aylesbury Vale over the next few days, with sunny spells and scattered showers.

Drier conditions are expected for Saturday and Bank Holiday Monday but, at the moment, Sunday is looking rather wet.

 

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