In the latest in the 'love for....' series, I am going to look at lacewings and allied insects - a much over-looked group of species, but nevertheless still fascinating and beautiful creatures!
Lacewings comprise the insect Order Neuroptera, of which there are around 76 species in the UK, including 1 species of antlion. You may be familiar with the commoner species of green lacewing, but there are in fact several species of green coloured lacewings and even more species that are brown. All lacewings and the antlion undergo a complete metamorphosis, meaning they have four life stages....ovum - larva - pupa - imago (adult), the same strategy used by other more familar insects such as beetles, butterflies and true flies. Most species are quite easy to tell apart with a guide book and a good hand lens, as the pattern of wing venation on many species is distinctive.
All species are predatory as both larvae and imago insects, having biting mouthparts that are used to catch and consume invertebrate prey. The larvae of the only UK species of antlion, or Euroleon nostras to give it it's scientific name, digs a burrow in sandy soil in which it catches ants and other insects.
Lacewings are as variable in size as they are in appearance, with the smallest species only reaching a wingspan of around 7-8mm and the largest, the giant lacewing, or Osmylus fulvicephalus having a wingspan of up to 5cm. If that isn't impressive enough, the antlion can be up to 30mm in length and have a 70mm wingspan.
Perhaps the most common species of lacewing that you will come across is Chrysoperla carnea, a large green lacewing, it is the only species that overwinters as an adult. You may find it hibernating in sheds and outhouses, as well as underneath leaflitter. But don't be fooled into thinking it is a brown lacewing - this species looses it's green colouration over the winter, developing into a brown-yellow colour, before regaining it's green colour again the following spring.
Green lacewing species - Chris Shields (rspb-images.com)
In addition to the 76 species of Neuroptera, there are 11 other insect species in the UK that are often associated with the lacewings, if not directly related to them.
The first of these are the Megaloptera, the alder flies. There are 3 species of alder fly in the UK, all in the Genus Sialis, the commonest being Sialis lutaria. Again, these insects have a four stage lifecycle and the larvae are aquatic and predatory on other invertebrates. The imago insects do not feed.
Sialis sp. Charlie Barnes
The Mecoptera comprise the scorpionflies. There are 4 species in the UK, 3 in the Genus Panorpa and the other known as the snow-flea, or Boreus hyemalis. Members of the Genus Panorpa are large, numerous and obvious insects in the summer months. They are predatory as both larvae and adults, the adults having a 'beak' containing biting mouthparts. The males have a scorpion sting-like tail, but this appendage in fact contains the reproductive organs, not a sting! The males can easily be separated by looking at the pattern on the tail, but the females are more difficult, requiring microscopic examination to determine species. The snow flea is distinctive by being active in winter.
A male scorpionfly, Panopra sp. Charlie Barnes
And last but not least (and perhaps my favourites!) are the Raphidioptera, the snake flies. There are 4 species in the UK, 3 of which are strongly associated with conifers. 1 species however, Phaeostigma notata, is associated with oak. The larvae and adults are predatory, the larvae feeding on other invertebrates under bark. You can see how they get their name, with the elongated prothorax, which they can raise above the rest of the body, giving the impression of a snake raising it's head. They can be fairly common, but very under-recorded in the UK and can be seen from May - September.
Snakefly species. Charlie Barnes