40 [Febniarj-, 



STYLOPIZED BEES. 



BY FREDERICK Y. THEOBALD, B.A., F.E.S., 



Cambridge University Extension Lecturer on Injurious Insects, Sfc. 



Mr. E-. C. L. Perkins' paper on Stylopized Bees shows us how 

 often observers disagree upon very important points. 8huckard, he 

 says, tells us that the larvae of Sti/Iops, feeding within the body of their 

 host, live upon the viscera and render the bee abortive, by destroying 

 the ovaries, since it is chiefly found to attack the female bees. In the 

 next paragraph Mr. Perkins says, " I never found the female more 

 liable to attack than the male, nor does the first part of his (Shuc- 

 kard's) statement agree with my observations on such British species 

 as I have examined." 



While Mr. Perkins' observations disagree, mine a^ree to a certain 

 extent with Shuckard's. In 1886 and 87 a large number of stylopized 

 bees came into my hands ; these were of a somewhat rare species, 

 Andrena lapponica. In the two years mentioned they were very 

 abundant in four localities near St. Leonards-on-Sea, but were ex- 

 tremely local. In 1887 I netted 180 specimens, of these 105 were 

 stylopized, but I only retained a few of each of the normal and 

 infested ones (in spirit). In 1888 they were decidedly scarcer, the 

 climatic conditions being much the same and the colonies undisturbed ; 

 this time I captured only 60 specimens, 54 being badly attacked. 

 Some of these were also put into spirit, and not " unearthed " until 

 1890, when my suspicion of the destruction caused by this parasite 

 was further aroused, by their disappearance in 1889 and 90 ; in 

 1889 a few were taken, but in 1890 they had entirely gone. I 

 naturally concluded that they had been exterminated by the Stylops 

 destroying the reproductive organs, as is done by some parasitic 

 Crustacea ; but not satisfied with this, I examined my spirit specimens 

 on my return to Cambridge. 



Eight out of sixteen examined had their viscera "crippled" to 

 such an extent that reproduction was impossible in both <^ and ? , 

 supposing the sexual products had been developed. Six out of the 

 eight were $ s ; two had two Stylops, the remainder one. The para- 

 sites in all eight cases had so pressed down the colon and cliylijic 

 ventricle that the vagina was flattened upon the ventral surface, the 

 spermatheca entirely absent, as were likewise the appendicular organs. 

 The ovaries were also flattened at their posterior extremities, and only 

 in one out of the six ? s was there any indication of developing ova 

 in the tubules, and these, if they reached maturity, were useless, as 



