WABNING COLOURS 213 



significance, enabling each bird to know its own eggs. 

 I owe this suggestive interpretation to my friend 

 Mr. Francis Gotch : it is greatly to be hoped that 

 experimental confirmation may be forthcoming. The 

 suggestion could be easily tested by altering the 

 positions of the eggs and modifying their appearance 

 by painting. Mr. Gotch's hypothesis was framed 

 after seeing a large number of the eggs of the guillemot 

 in their natural surroundings. It appears to be a 

 more feasible explanation than that offered by Mr. 

 Wallace. ' The wonderful range of colour and marking 

 in the eggs of the guillemot may be imputed to the 

 inaccessible rocks on which it breeds, giving it com- 

 plete protection from enemies ' (loc. cit. p. 214). 



Recognition Markings in Insects 



Turning to insects, I do not believe with Mr. 

 Wallace that colours and markings generally are to 

 be explained in this way, although many instances 

 of undoubted recognition characters will probably be 

 found among them. In fact, a very interesting 

 example only recently came before me. 



It has been already mentioned that Lepidopterous 

 larvaB are especially subject to the attacks of parasitic 

 insects (Hymenoptera and Diptera), which lay their 

 eggs in or upon them. It is of the highest importance 

 for a parasite to know whether a larva is already 

 * occupied,' and also to ensure that other parasites 



