1918. j 117 



confirmation : — H. riiliciindus Chr., H. 4-notf(fi(s K., II. alhipes K., 

 H. longitlus Sm., H. miniUissimus K., II. minutiis K., and //. morio 

 F., and I think also II. leucozonhis. 



The ett'ect of stylopization on the internal reproductive organs of 

 Andrena has been insufficiently studied in this country, and the 

 accounts given by difterent workers are not in accord. It must be 

 remembered, however, that each writei* on tlie subject examined different 

 species of Andrena^ and, it is possible that the effect of the parasite is 

 not the same ni the case of different hosts with different species of 

 Stglops. My earliest investigations (Ent. Mo. Mag. 1892, p. 1) were 

 made mainh^ on stylopized A. tvllkella K. and saiindersella Perk. 

 {nana E. Saund.), while those of Theobald (/. c. p. 40) were on 

 A. apicata Sm. (then wrongly known as A. lapponica Zett.) and his 

 conclusions were ver}^ different from mine. Kecently (Quart. Journ. 

 Micr. Sci. 1914, p. 435), extensive work was done on A. nigroaenea K. 

 by Geoffrey Smith and A. H. Hamm. It will be noted then that the 

 Andrena mainly used by each writer belonged each to a quite distinct 

 group of species in this large genus. The conclusions arrived at by the 

 last-named authors agree very well with my ow^n. It is true that they 

 say that both '• for male and female " m}^ notes '' tend to minimise the 

 effect of the parasites on the internal organs.'' For reasons stated 

 (viz. the fact that the female ovaries are often unripe in freshly emerged 

 bees, while the S genitalia are fully-developed at that period) my 

 dissections were practically all made from males, as I was careful to 

 point out, and the results obtained from an examination of these appear 

 to me to exactly agree with those of Smith and Hamm. Thus of 15 

 cT nigroaenea examined (4 of which carried <S puparia and 10 female 

 parasites, while one had a 6 and $ parasite) they found that " it 

 could not be observed that the presence of parasites in any case had 

 exerted any effect on the development of the testes and ducts." Perez 

 in his classical w^ork on the subject of stylopization records some cases 

 of damage to one side of the testes as due to Stglops. This may be 

 correct, but his account of the external changes caused b}^ st3dopization 

 in some common Andrenae does not agree with the facts observed in 

 liritish examples of these same species of Andrena, so far as we 

 can see. 



From Perez's original observations and the recent ones of Smith 

 and Hamm, it is certain that the ovaries of the $ bee are always or 

 nearly always reduced in size or at least fail to produce ripe ova. 

 It would be of great interest to compare the condition of these parts 



