20 HYMENOPTERA CHAP. 



development of the imago takes place gradually though quickly. 

 Some larvae spin cocoons, others do not. 



A very large number of bees are parasitic in their habits, 

 laying an egg, or sometimes more than one, in the cell of a work- 

 ing bee of some species other than their own ; in such cases the 

 resulting larvae eat and grow more quickly than the progeny of 

 the host bee, and so cause it to die of starvation. It has been 

 observed that some of these parasitic larvae, after eating all the 

 store of food, then devour the larva they have robbed. In 

 other cases it is possible that the first care of the parasitic larva, 

 after hatching, is to eat the rival egg. 



The taxonomy of bees is in a very unsatisfactory state. The 

 earlier Hyinenopterists were divided into two schools, one of 

 which proposed to classify the bees according to their habits, 

 while the other adopted an arrangement depending on the length 

 of the parts of the mouth, the development of the palpi, and the 

 form and positions of the organs for carrying pollen. Neither 

 of these arrangements was at all satisfactory, and some ento- 

 mologists endeavoured to combine them, the result being a 

 classification founded partly on habits and partly on certain 

 minor structural characters. This course has also proved unsatis- 

 factory ; this is especially the case with exotic bees, which have 

 been placed in groups that are defined by habits, although very 

 little observation has actually been made on this point. 

 Efforts have recently been made to establish an improved classifi- 

 cation, but as they relate solely to the European bees they are 

 insufficient for general purposes. 



The more important of the groups that have been recognised 

 are (1) the Obtusilingues, short-tongued bees, with the tip of the 

 lingua bifid or broad; (2) Acutilingues, short-tongued bees, with 

 acute tip to the tongue ; these two groups being frequently treated 

 of as forming the Andrenidae. Coming to the Apidae, or the 

 bees with long and folded tongues, there have been distinguished 

 (3) Scopulipedes, bees carrying pollen with their feet, and (4) 

 I>asygastres, those that carry it under the abdomen; some of the 

 p;irasitie and other forms have been separated as (5) Denudatae 

 (or ( 'iietilinae) : the l>ombi and the more perfectly social bees 

 forming another group, viz. (G) Sociales. A group Andrenoides, 

 or Pan urg ides, was also proposed for certain bees considered to 

 belong to the Apidae though exhibiting many points of resent- 



