Home All ➤ The three Ps: Tillids, Sillids and Sockids

➤ The three Ps: Tillids, Sillids and Sockids

Published on December 6, 2014, by in All, News and musings.

During our evaluation of the invertebrate diversity of the sites in Bedford, Luton and Milton Keynes, we have been seeing many of the less well-known insects. Among them are the somewhat confusing, Feather-wing Beetles, Plant Lice and Booklice. Confusing, not because of their appearance, but because of the difficulty remembering their names! Respectively, the correct scientific names for these families of animals are; Ptiliidae, Psyllidae and Psocidae, all with their silent P.

The Ptiliids are the tiniest of all beetles, with adults ranging from 0.3 mm to a maximum of 4mm. They possess the most delicate wings, with feathery edges, which are probably more useful for catching a breeze, than for direct flight. Astonishingly, the feather-wing beetles produce only one egg at a time; but it may be almost half the size of the female!



The Psyllids look a lot like Aphids and are probably often overlooked in your garden as being just another greenfly. They are, again, very small (1.5-4.5 mm in length) and are characterised by their strong hind legs that allow them to jump. Males also often have a noticeable upturned tip to the abdomen, with the genitalia sitting upwards. They are very host specific and a particular species will usually only be found on a specific species of plant. For example, Psylla buxi only completes its lifecycle on Box trees. Another species, Spanioneura fonscolombei is also restricted to Box trees. Infestations of these insects can harm a plant and Psylla mali and Psylla pyricola are well-known pests to Apple and Pear growers. Several species of psyllid produce a waxy silk-like secretion which offers some degree of protection from predators. It may just look like a white, flaky powder on the leaves of the plant, but closer examination may reveal a sheltering psyllid.



The Psocids are known as booklice (indoors) or barkflies (outdoors). They are very small (1-10mm) and could be mistaken for psyllids, however, they rarely fly or jump when disturbed. Psocids are often wingless and have a fairly distinctive large, wide head, like a dragonfly larva. Males do not have the upturned abdomen of the psyllids. They feed on microflora, such as algae, lichens and fungi, but also on dry, powdery food products. Booklice are usually feeding on the microscopic mould or binding glue of old books. They may also be seen on new plaster walls or concrete floors, where the drying plaster offers a nice damp habitat with the growth of tiny moulds, on which the psocids feed. But you have to look VERY closely.



Identifying (and pronouncing the names of) these insects correctly has been an important part of the data gathering for the F3UES project. In order to evaluate the relationship between the variety of animals using our cities, the structure of habitats, and their impact on local people, we need to correctly recognise even the tiniest inhabitants. Whether they are a food source for other animals, a pest limiting the growth of plants or an essential pollinator, it is the tiny, unseen creatures that can offer fascinating insights into these ecosystem interactions. Distinguishing between our ptilliids, psyllids and our psocids may just illuminate something as yet unseen in our quest to understand the functions of our urban green spaces. We need to stay alert to recognising all of the components that are making up the wild life on our doorsteps. Ptill next time …

Paul Richards

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