378 THE MAINTENANCE OF THE INDIVIDUAL 



Native Behaviors May Be Modified 



Although native behavior is usually predictable, there is some 

 evidence that it may be modified under certain conditions. Howes ^ 

 gives such a case. The sphecid wasp places a single paralyzed cicada 

 in its burrow after laying an egg in the body of the unfortunate vic- 

 tim. The burrow is then sealed with earth, the young wasp feeding 

 on the paralyzed insect until the larva pupates. The adult wasp 

 carries the cicada, which is larger than itself, by means of two power- 

 ful up-turned hooks on each side of its hind legs. Howes removed 

 these hooks from the legs of a sphecid wasp and after several hours 

 replaced the wasp near the burrow, but close to a cicada which it 

 had previously captured and paralyzed. The wasp paid no attention 

 to the cicada but flew off, shortly returning with another victim 

 which it carried between the first and second pairs of legs. This 

 shows a marked modification of its original instinctive behavior. 



The following examples show how in two nearly related species there 

 may be differences in behavior. The mud-dauber wasp builds a 

 small nest of from eight to ten cells, filling each cell with paralyzed 

 insects or spiders which are used as food for the developing young. 

 In filling the cell, Howes found that the wasp averaged one spider for 

 every seven minutes of time until its tenth visit, when it brought a 

 small pellet of mud which it flattened and placed across the opening of 

 the cell. This was not enough to close the cell, so the insect flew away 

 to get more mud. While it was gone Howes removed the spiders and 

 the cell cap. The wasp, upon returning, resealed the cell without 

 examination and without depositing spiders or another egg. In the 

 case of the paper wasp, a near relative, when Howes replaced an 

 unfinished cell with one of papier-mache the wasp immediately tore 

 the papier-mache cell down and proceeded to build a proper one. 

 This indicates that the chain of native behaviors in some cases may 

 never be broken without a complete re-acting of the whole scene, 

 while in others modification of behavior which looks like a low-grade 

 intelligence is found. 



In considering the insect with its "bag of tricks," all of which can 

 be played expertly but which cannot be changed, we must think in 

 terms of structure as well as in terms of function. Contrast, for 

 example, the strongly built claws, legs, or mouth parts of an insect, 

 or a crustacean, with the hands of a man. The former, each of which 



I Howes, P. G., Insect Behavior, Badger, 1919. 



