September 1, 1897.] 



KNOWLEDGE. 



203 



grudge for destroying many of their rarest captures of 

 larvsE and pupse. We can all remember the bitter disap- 

 pointment experienced on iinding a round hole in a pet 

 pupa, and, instead of the expected moth, a tierce and 

 active four-winged ichneumon fly. Time softens our 

 disappointment, and now we prefer the parasite. It is 

 a pleasure to record the fact that the members of the 

 South London Entomological Society are all contributing 

 specimens of parasites bred each season. The collection 

 is assuming great importance, and will be of considerable 

 assistance to future students of this much-neglected branch. 



As we are briefly running through the Hyivenoptera our 

 difficulties seem to increase, for with the next division, the 

 Chalcidida, we hardly know what to do, or to whom we 

 can turn for assistance in naming these brilliantly 

 spangled green and gold coloured flies, whose " name is 

 legion." The labourers in this field are indeed few, so 

 much so that there is not a "specialist" even at the 

 Natural History Museum, South Kensington. Among 

 the British bees and wasps we have an able and willing 

 helper in Mr. Edward Saunders, to whom I am personally 

 indebted for help time after time. A few years ago I was 

 enjoying a short holiday at Portland, where, during a 

 sudden burst of sunshine, I caught a few (as I thought) 

 " common things," which I sent on to Mr. Saunders 

 to name. His reply informed me that one of the specimens 

 was of great rarity, being the second on record of Aporus 

 bicolur. The wood and sand boring wasps (Crabronida) 

 are of immense interest from their habit of storing up, for 

 their future progeny, insects of various orders. The 

 large Crnhro rribrurius searches for craneflies, whereas 

 another collects certain species of Si/rphuf:. At the 

 present time I have several species under close observa- 

 tion, and have already observed Crahm cribmn'us take 

 over two dozen craneflies down its burrow, and, strange 

 to say, these are not of a common species. Years ago 

 at Hampstead Heath there used to be a corner known as 

 the " horse exercise ground," bounded on one side by a 

 high grassy bank, in which various bees had colonized, 

 notably Eucera longicornis : adjoining this bank was a 

 yellow sandbank, fairly riddled with holes, made by 

 Cerceris arenari((. At the time I speak of (twenty years 

 ago) one could sit down in peace and quietly watch these 

 industrious insects bringing in their provisions for their 

 future progeny. These provisions always consisted of 

 Strophosomns obestis, a beautiful beetle whose elytra are 

 covered with broad scales, giving the creature the appear- 

 ance of being clothed in bronze coinage. The nearest 

 spot where I found these beetles was at Highgate Woods — 

 another old collecting ground, but not now. Others of 

 this family collect spiders, frog-hoppers, etc. 



Works on ants are fairly plentiful, but we don't know all 

 their ways yet. If anyone be desirous of studying the 

 ways of Forinicii rufa, the wood ant, I can confidently 

 recommend St. George's Hill, Weybridge, as a good 

 locality where you can see, hear, smell, and feel them ! 

 But you may have too much of the latter sense, so I 

 advise coat sleeves and trousers bottoms to be tied up 

 tightly, and a green net put over the head and tied as 

 tight as bearable round the neck. Some of the " ant- 

 hills " are two feet high, and anyone who wishes to see 

 insect life has only to place a walking stick in the centre 

 of the heap of pine needles — but making observations and 

 notes on the spot is decidedly lively work. 



Having briefly indicated how many fruitful fields are 

 open for the industrious student of entomology, let us 

 go back to one of those " neglected families " which have 

 received but small attention. One reason for this want of 

 attention is, no doubt, because of the extreme smallnesa 



of the members of this family, the largest being not more 

 than one-twentieth of an inch long, whereas the smallest 

 is less than one eighty-fifth of an inch from head to tail. 

 These insect atoms have been classed among the Chal- 

 cididte by Haliday — the originator of the Mymaridcs — who 

 first noticed them in 1833. Since that date Westwood has 

 placed them among the Proctotrupida : and now Ashmead — 

 author of American Proctotripida^i&s decided in favoui' 

 of Haliday's arrangement, and in this I fully concur. 



The fairy flies are, without doubt, among the many won 

 derful parasitic thjmenoptera, the most admirable in their 

 exquisite structure, as well as in their habits and economy. 

 All the species are egg parasites, and each species has its 

 peculiar taste, selecting with unerring instmct the right 

 kind of egg — generally that of an injurious insect— in 

 which the female lays one of its own eggs, which in due 

 time hatches or develops into an active maggot. This 

 maggot feeds upon the contained fluids, and finds suflicient 

 nutriment to bring it to full size, when it assumes the 

 pupal stage. The fly, being matured, bites out a round 

 piece of the egg shell large enough to allow it to escape. 

 The most noticeable character in the fairy flies is the 

 transverse line across the face a little above the insertion 

 of the antenniB. The wings are devoid of all wing nerves, 

 for the subcostal is so short and stumpy that the wing 

 looks perfectly free. Both the upper and under surfaces of 

 the wings are covered with minute hairs, and the margins 

 of both wings are surrounded by long hairlike cilice. 



Owing to the kindness of the authorities of Dublui 

 Museum, I have been permitted to make a most exhaustive 

 and critical examination of Haliday's type collection of 

 British Myiiiarida, and though the hand of time and those 

 of others have materially interfered with their original 

 arrangement, the result has been most satisfactory to me. 

 Although one or two of the most interesting types are 

 absent, I have been enabled to re-establish Haliday's genus 

 Panthua, which certain compilers had, for no apparent 

 reason, ignored. I found two specimens stiU bearing 

 the old labels, and after long and critical microscopic 

 examination I saw that both were distinct from any 

 others. I applied for and obtained permission to remove 

 the carded specimens, and remount them in Canada balsam. 

 This was successfully done, and on making a photo-micro- 

 graph the peculiar generic characters were brought out 

 most distinctly. Some naturalists appear to imagine that 

 a pocket lens will be sutificient to identify these species, 

 but in an insect which is but a fiftieth or an eightieth of 

 an inch long it is of absolute importance that every joint 

 and detail should be examined under the microscope, and 

 the relative proportion of each joint of the antennae be 

 compared with closely allied species — ^just as they are with 

 all large Hijinenoptera. The curve, too, of the delicate 

 wings is a most important feature which must not be 

 hurried over. This point leads me to speak of the 

 immense superiority of photo-micrographs over drawings 

 of these fairy flies. No matter how exact an enthuaiastic 

 naturalist may be in his endeavours, it is a physical 

 impossibility for anyone to follow out and reproduce the 

 exact curve of these microscopic wings ; and as the flies 

 when properly prepared and " set " in Canada balsam lend 

 themselves peculiarly to photo-micrography, it is wise to 

 take advantage of this. The details can afterwards be 

 drawn to a much larger scale. It is my intention to do 

 this with every species which I have collected during the 

 past twenty years, and of which I have a very large 

 number, far exceeding those known to science. The 

 illustrations accompanying this short article will, I think, 

 show what exceedingly good subjects the fairy flies are 

 for photo-micrographs. 



