SOME WINGLESS INSECTS 159 



Another tiny whitish psocid (Clothilla pulsatoria) rarer than 

 Atropos but similar in its mode of life, has minute wing- 

 rudiments in the adult state ; as in the forms of Mesopsocus 

 mentioned above, the wingless condition has not been fully 

 attained, or, as the process is often described, wings have 

 not been altogether lost. The varying condition as regards 

 wing-development in members of the same family and the 

 same species suggest inevitably that this mode of expression 

 is justified, and that in such a group of the Mallophaga, whose 

 relationship to the winged Psocidae is admitted, we may 

 conclude that the normal growth of wings has been entirely 

 suppressed as an accompaniment of their parasitic mode of 

 life. It is worthy of mention that, while among the winged 

 psocids, the prothorax is extremely reduced in extent so as 

 not to be visible from above, it retains its original importance 

 in the plan of the body in those members of the family whose 

 wings are reduced or wanting. Such a fact points to the 

 wingless condition as of the nature of a reversion to primitive 

 or immature conditions. 



Some modern students 1 of the Anoplura the true or 

 sucking lice consider them to be allied to the Mallophaga 

 despite the suctorial nature of the anopluran mouth, which 

 has been generally held to indicate affinity to the Hemiptera 

 the order which comprises bugs and their allies. In con- 

 nexion with the subject of winglessness as an accompaniment 

 of parasitism, it is instructive to turn to a notorious member 

 of the Hemiptera, the Bed-bug (Cimex lectularius, Fig. 91). 

 This hairy, hard-cuticled little parasite, with its prominent 

 eyes and lobed prothorax, its broad, rounded abdomen, and 

 its flattened form adapted for concealment in cracks and 

 crevices, has the hindwings entirely wanting, while the fore- 

 wings are represented by small, firm, hairy pads. Besides the 

 development of these pads, the only noteworthy change 

 experienced during the bed-bug's life-history is the elaboration 

 in form of the prothorax, which, undistinguished in the newly- 

 hatched young, has in the adult two prominent, forwardly- 

 directed, rounded lobes. It is interesting to find that the 

 family (Cimicidae) to which the bed-bug belongs comprises 



1 E. Mjoberg : " Studien uber Mallophagen und Anopluren ". Ark. /. 

 Zoo/. (Stockholm), VI. 1901. 



