138 



KNOWLEDGE & SCIENTIFIC NEWS. 



[July, 1904. 



as these butterflies are accustomed to go to roost long 

 before twilight has settled in, it is quite likely that their 

 shape and colouring protect them from the attacks of 

 birds. 



Perhaps the most curious case of protective flower 

 resemblance is that vouched for by Professor Ciregory, 



Individuals of a Species of I'Uila grouped upon a Plant Stem. Note 

 flower-like appearance. 



and described in his work, " The Great Rift \'alley." 

 The insect in question is a species of Flata, which is a 

 genus allied to the scale-msects, and to the Apliida. 

 The species described by Professor Gregory is indigenous 

 to British East .Africa, and is dimorphic — a certain 

 number of indixiduals of each sex being bright pink in 



colour, while others are bright green. These insects 

 resemble the green fly, or Aphida, in habits, sitting 

 motionless on plant stems for long periods and feeding 

 upon the sap. The manner in which the individuals of 

 the present species are said to group themselves is very 



A green Mantid, from Ceylon, lying in wait among foliage. 



Brown Mantid. from Usambava, at rest on bark. 



remarkable. The pink ones sit upon the lower part of 

 the stem, while the green ones have their place above, 

 towards the extremity. Further, the developing larvae, 

 which secrete long filaments of a waxy substance, and 

 are quaint, fluffy little objects, sit beneath the pink indi- 

 viduals at the lowest part of the stem. Thus, the exact 

 appearance of a spiked inflorescence is simulated. 

 The fluffy larvre have a distinct likeness to seed 

 poJs. Tiie pink individuals might be mistaken 

 for drooping flowers, while the green ones, higher 

 up the stem, look like so many undeveloped 

 buds. Professor Poulton, however, has re- 

 marked that the grouping of green and pink 

 insects in Professor Gregory's observation was 

 probably accidental. 



So far, we ha\ e examined only instances of 

 protective resemblance — instances, that is to 

 say, in which the colours, or the colours and 

 form, of an insect are seen to be of value to it as 

 a means of escaping detection. W'e have now 

 to consider cases in which the appearances of 

 insects, while possibly screening them from 

 the attacks of their enemies, have the additional 

 advantage of enabling them to approach un- 

 observed the creatures upon which they them- 

 selves prey. Such instances of resemblance 

 may be termed aggressive. 



The curious "praying insects," or Mantidie, 

 afford many striking examples of aggressive 

 resemblance. The whole of this large family 

 is insectivorous in habit, and the majority of 



