Sunday, July 18, 2010

Plague of Pollen Beetles

If you live downwind of an oilseed rape field, the chances are that you'll be well-acquainted with these tiny pollen beetles Meligethes aeneus., which are only a few millimetres long but take to the air in billions. When they emerge from pupae in the soil in spring they lay their eggs in flower buds of rapeseed flowers. When they're fully feed the grubs pupate in the soil then emerge in mid-July, in vast numbers.  Blown downwind, that's when they descend on gardens, infesting flowers in their hunt for pollen. They've become a major pest of the oilseed rape crop and have now developed resistance to pyrethroid insecticides in many areas of Europe where the crop is grown.

They'll eat pollen wherever they can find it (the keel petals of sweet peas are a favourite destination in my garden), but are particularly attracted to yellow blooms, like this sow thistle...

... and this hawkweed....

... and this buttercup.

The only comfort is that they are probably a very useful food source for swallows, swifts and house martins which catch them in large numbers in flight.

6 comments:

  1. They're also on my Shasta Daisies..... and the washing hanging on the line. :O)

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  2. These do seem to get everywhere don't they lol
    That Sow Thistle has attracted them like a magnet.

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  3. I have noticed this year there does seem to be an explosion of these little beetles.

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  4. Hi Lesley, I've seen them on yellow cars too...

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  5. Hi Keith, I think they're a problem for people who cut flowers from a garden and bring them indoors. Beetles everywhere...

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  6. Hi Linda, they are becoming a major pest of oilseed rape crops everywhere

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