STREPSIPTERA. 



short, slender, and compressed, with the tarsi fur- 

 nished with fleshy cushions, but destitute of claws ; 

 the two anterior pair of legs are close together, and 

 the posterior pair very far behind. The abdomen 

 is small and scarcely coriaceous ; it is cylindric, eight 

 or nine-jointed, and furnished with a recurved point. 



These insects are of small size, and in the larva 

 state they are parasitic in the bodies of various spe- 

 cies of wild bees (Andrenidte), and wasps ( Vespidce}. 

 The order was first detected by Rossi, an Italian 

 entomologist, who discovered its habits, and formed 

 a genus for the reception of the species which he 

 discovered (Xenos vesparum, Rossi ; Xenos Rossii, 

 Kirby), but he regarded it as belonging to the order 

 Hymenoptera. Mr. Kirby having discovered another 

 species belonging to the same group, but to a distinct 

 genus in this country, and having received another 

 species from Professor Peck of America, investigated 

 the subject very minutely, and detailed the characters 

 of the order and its genera in an elaborate Memoir 

 published in the Linnsean Transactions. The fol- 

 lowing is Mr. Kirby's account of his discovery of 

 the English species, and as it is illustrative of the 

 habits of the insect, we shall quote it at length. 

 Having observed upon various species of Andrena 

 " something that I took to be a kind of acarus, which 

 appeared to be immoveably fixed just at the inoscu- 

 lations of the dorsal segments of the abdomen, and at 

 length finding three or four upon a specimen of Me- 

 litta (Andrena) nigrocenea, I determined not to lose 

 the opportunity of taking one oft' to examine and 

 describe ; but what was my astonishment, when upon 

 my attempting to disengage it with a pin, I drew 

 forth from the body of the bee a white fleshy larva a 

 quarter of an inch in length, the head of which I had 

 mistaken for an acarus ! After I had examined one 

 specimen, I attempted to extract a second, and the 

 reader may imagine how greatly my astonishment 

 was increased, when, after I had drawn it out but a 

 little way, I saw its skin burst, and a head as black 

 as ink, with large staring eyes and antennae consisting 

 of two branches, break forth and move itself briskly 

 from side to side. It looked like a little imp of 

 darkness just emerged from the infernal regions. My 

 eagerness to set free from its confinement this ex- 

 traordinary animal may be easily conjectured. In- 

 deed, I was impatient to become better acquainted 

 with so singular a creature. When it was completely 

 disengaged, and I had secured it from making its 

 escape, I set myself to examine it as accurately as 

 possible, and I found, after careful enquiry, that I had 

 got a nondescript, whose very class [order] seemed 

 dubious." Monograph. Apum Angl. ii., 113. 



Mr. Dale, who has been very successful in the dis- 

 cover}' of insects of this order, communicated the 

 following observations to Mr. Curtis, by whom they 

 were published in the British Entomology, fol. 226, 

 together with a beautiful illustration of Stylops Dalii 

 (fig. A, natural size ; B, magnified ; c, the andrena 

 with the heads of two of the larvae exposed between 

 the segments of the abdomen ; D, larva extracted and 

 magnified), a species named after the gentleman above 

 mentioned, and whose remarks are as follows : 



" Every specimen of Andrena barbilabris, I have 

 seen this year [1828?], from the 27th April to the 

 4th June, have contained larvae, pupae, or exuviaa of 

 Stylops, from one to three in each. On the 5th May, 

 I picked out one with a pin ; on the 7th another 

 rather immature, and caught one flying in the hot 



sunshine over a quickset hedge in the garden j it 

 looked milk white on the wing, with a jet black body, 

 and totally unlike any thing else ; it flew with an un- 

 dulating or vacillating motion amongst the young 

 shoots, and I could not catch it till it settled on one, 



when it'ran up and down, its wings in motion and 

 malting a considerable buzz or hum nearly as loud as 

 a Sesia ; it twisted about its rather long tail, and 

 turned it up like a Staphylinus. I put it under a 

 glass and placed it in the sun ; it became quite furious 

 in its confinement, and never ceased running about for 

 two hours. The elytra or processes were kept in 

 quick vibration as well as the wings ; it buzzed against 

 the sides of the glass with its head touching it, and 

 tumbled about on its back. By putting two bees 

 (Andrena labialis] under a glass in the sun, two 

 Stylops were produced ; the bees seemed unea?y 

 and went up towards them, but evidently with cau- 

 tion as if to fight, and moving their antennae towards 

 them retreated. I once thought the bee attempted 

 to seize it ; but the oddest thing was to see the Sty- 

 lops get on the body of the bee and ride about, the 

 latter using every effort to throw his rider. A large 

 hole is left in the tail of the bee where the Styles 

 escapes, which closes up after a time. I have found 

 five species of Andrena infested. When off the bee 

 the Stylops kept its wings still and half erect." 



From the recorded observations of Jurine, it is 

 evident that the pupa state of these insects corre- 

 sponds with that of many Diptera in being coarctate, 

 that is, enclosed in the skin of the larva ; it also ap- 

 pears probable that it is not until the larva is full- 

 grown, that it protrudes its head out of the body and 

 between the abdominal rings of the bee ; but there 

 are still many questions relative to the natural history 

 of these singular creatures, which still remain unas- 

 certained. Some curious speculations naturally arise 

 from the remarkable fact observed by Mr. Pickering, 

 of which the details are published in the last part of 

 the Transactions of the Entomological Society, and 

 by whom an Andrena was found in the winged state 

 in its cell under ground at the end of the month of 

 December (which had evidently only recently quit- 

 ted the pupa state), and from the abdomen of which 

 he extracted a perfect species of Stylops (S. Spencii), 

 as well as a specimen of the larva. The following 

 queries are suggested by Mr. Pickering as embracing 



