96 W. COLE ON A PARASITE OF HUMBLE BEES. 



of the bee. They are occasionally entangled with one of the trachea?, 

 but this seems to be a purely accidental circumstance. They 

 are generally more or less coiled up, and are absolutely without 

 motion. One very noteworthy fact is that the worms have hitherto 

 only been found in large female bees ; so far as present observation 

 goes, the male and worker humble-bees are entirely free from 

 their attacks. This predilection for one sex is by no means a solitary 

 instance amongst the Entozoic parasites of the Hymenoptera ; 

 Siebold describes a species of Gordius which affects the drones of 

 the honey-bee, and Mermis albicans is said to have similar habits. 



Leon Dufour's original specimens of Sphwridaria were found in 

 the large and handsome humble-bees known to entomologists as 

 Bombus terrestris, and Bombus hortorum. Sir John Lubbock 

 and myself have found it by far the most commonly in B. terrestris ; 

 but from six to eight species of Bombus are more or less liable to 

 attack. The spring of the present year seemed to be peculiarly 

 favourable for the increase and well-being of the parasite ; and I 

 think I am quite correct in saying that from the middle of May 

 until the beginning of June I never examined a single female B. 

 terrestris without meeting with some specimens. On May 31st 

 they reached a climax in point of numbers, one bee containing no 

 less than 33 mature Sphcerularice of about half the normal size, in 

 addition to myriads of eggs and young. All these Bombi were 

 caught quite indiscriminately, as they frequented the luxuriant 

 blossoms of a plantation of rhododendrons on the confines of 

 Epping Forest ; and I narrowly watched the flight and behaviour 

 of the females in which SphosrularicB were afterwards found in 

 plenty, but could never convince myself that they were less active 

 than the general run of these busy creatures. It is, however, 

 difficult to believe but that such a large number of parasites must 

 have a very injurious effect on the life of the bee, and, perhaps, 

 their presence or. absence may be one of the determining causes of 

 the scarcity, or otherwise, of humble bees in some years. From 

 the end of May I had no further opportunity of examining humble 

 bees before the wet weather set in ; and either the rain or the 

 plague of Sphceru-laria so thinned the ranks of the insects that the 

 results of two or three excursions, made at the end of July and the 

 beginning of August for the special purpose of searching for them, 

 were perfectly fruitless, not a single individual of the larger Bom bi 

 being observed. 



