Mealy Plum Aphid (Hyalopterus pruni)

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It seems like 2023 is a bumper year for aphids. Nearly all the trees and bushes in the garden are covered in aphids and sticky with honeydew. This time the plum tree is heavily infested with Mealy Plum Aphids; another new species for the list as I didn’t record these before. Hopefully it will also be a bumper year for things that preys on aphids too, like ladybirds. The blue tits from our nest box are trying, but struggling, to keep on top of the problem.

#933 Mealy Plum Aphid (Hyalopterus pruni)

Woolly beech aphid (Phyllaphis fagi)

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A large beech tree shades a chunk of the garden, plus it is being used as a roost for woodpigeons which crap all over the patio (just how much does a single pigeon produce in a day!?). Anyhow, cutting some low hanging branches in the hope the pigeons find a new roost site, they were all sticky and the under-sides of the leaves covered in clusters of fluffy white insects. These are Woolly Beech Aphids (Phyllaphis fagi, #927), which secrete copious honeydew. I didn’t notice them previous years, or that the tree was buzzing with insects attracted by the honeydew.

#927 Woolly beech aphid Phyllaphis fagi

Californian Maple Aphid (Periphyllus californiensis)

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Spotting my regular pair of long-tailed tits feeding on a small Japanese Maple, I thought it worth checking what they were going after. It turned out to be a pretty heavy infestation of honey-dew secreting aphids; in this case Californian Maple Aphids (Periphyllus californiensis). These are not native to UK, as you might guess from the name, though in fact they come originally from East Asia rather than the USA, but have now spread more or less globally wherever ornamental garden maples are grown.

#916 Californian Maple Aphid (Periphyllus californiensis)

Woolly Aphid (Eriosoma lanigerum, #863)

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Not wholly welcome, but one of the apple trees has a minor infestation of these Woolly Aphids (Eriosoma lanigerum). At first I thought it was mildew, but inside the while sticky wool there are lots of dark-coloured aphids. The colony was attended by some Harlequin Ladybirds, so hopefully natural predation can keep the aphid population under control.

Sage Pests

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My Sage (Salvia officinalis) bush is a right mess at the moment. I should have pruned over the winter, but looking closer it is also heavily infested with insects. It is always hopping with Sage Leafhoppers (Eupteryx melissae), bugs that leave white spots all over the leaves where they suck the sap. But it is even more ratty than previously due to aphids. Researching these (recommended looking at https://influentialpoints.com), these are Sage Aphids (Aphis passeriniana). This species is considered rare in UK, with only 3 records up to 2018, the nearest in Sussex. Judging from the number on my Sage, they seem to find Gloucestershire to their liking, and are likely on the increase in UK.

Probably the Largest Parthenogenetic, Aestivating Aphid in the World

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These Giant Willow Aphids (Tuberolachnus salignus, #389) skipped a year last winter, but this winter they are back in several groups on the undersides of the smaller branches in my willow tree. You’d think, exposed on the bare winter branches, they would be easy prey for the birds, but despite being big enough to make a good meal they seem not to get consumed to any appreciable extent. Neither do they seem susceptible to cold, they just hang in there on the branches right through the winter.

According to other accounts, these aphids should appear in late summer, but mine I’m sure only emerge from October onward; then in the early spring they disappear again, nobody really knows where. This summer dormancy is called aestivation (kind of the opposite of hibernation), which several species do - normally to avoid excess heat and drought in the summer.

Another thing that’s fascinating about the Giant Willow Aphid is that there are no males present in the colony. In fact no males of this species have ever been recorded anywhere. The females give birth to live young which are clones of their mother - this is referred to as parthenogenesis.

It’s interesting that despite looking I didn’t see a single one last winter, so maybe just to make it extra difficult for any predators or parasites to come to rely on them as a food-source, these insects ave a two year life-cycle. It will be interesting to see if I find any next year.

389 Giant Willow Aphid.jpg

Pests on my Veg Seedlings

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Spectacular damage in the space of a few days to my Mizuna (Japanese mustard greens) and Swede seedlings. The final picture, of a Small White Butterfly caterpillar, was taken on 5th July and the first photo of the same leaves, devastated by flea beetles, on 16 July. Partaking in the feeding frenzy, four species of Brassica pest, all new to the list.

The main culprits were tiny black Cabbage-stem Flea Beetles (Psylliodes chrysocephala, #649) that eat little holes in the leaves of many types of Brassica. I also found one Lesser Striped Flea Beetle (Phyllotreta undulata, #647), with a cream-coloured stripe on its flanks. Both the Swede and Mizuna plants also had an infestation of Cabbage Stem Weevils (Ceutorhynchus pallidactylus, #468). The final pest, just on the Swede plants, was Mealy Cabbage Aphid (Brevicoryne brassicae, #650), with this winged adult, but also a fair few green coloured wingless immature aphids on the undersides of the leaves.

Thousands of Aphids

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I’m not sure if it’s the cold spell weather we’re having or the season. but after all the activity around the early bees and butterflies there’s a noticeable lull in activity around the garden. One family of insects that is bucking this trend though are the aphids; there’s thousands of them everywhere and the predator species like ladybirds are not around in any kind of numbers sufficient to keep the numbers down. Who knows, maybe that’s by design - to let the numbers get up so that there’s plenty to eat for the rest of the summer. It’s very well organised if that’s the case.

The aphids I found lately are Gooseberry Willowherb Aphid (Aphis grossulariae) scrunching up the new grown leaves on the gooseberry bushes, Silver Birch Aphid (Euceraphis betulae) in amazing numbers on the undersides of the silver birch leaves, Geranium Aphid (Acyrthosiphon malvae) on the lower leaves of the wild geranium plants in the flowerbed and Herb Bennet Aphid (Macrosiphum gei) on the Herb Bennet that grows wherever it can.

One thing i learned about aphids is that certain species have a life-cycle involving two plants - the Gooseberry Willowherb Aphid being an example. It spends the winter and spring in the woody gooseberry bush, in the spring curling over the young leaves at the ends of each branch as the first generations of young grow. Presumably this is for protection against things like the blue tits and wren that I have seen feeding in the same bush. In the summer they decamp, at least partially, to willowherb plants, before returning to the gooseberry to pass the winter. Apparently several aphid species have a similar strategy; while it makes sense in terms of surviving the winter it seems incredible that a species would evolve to be dependent on two specific yet so different species of plant.