A Preliminary Experiment on the Removing the Obstacle from the Nest in the Ant-lions

Abstract

There are recognized three types of removing the obstacle from the nest, RB I, II and III, in the ant-lions. They remove the obstacles (the pieces of rubber in this experiment) from their nests with their posterior or dorsal parts of abdomens while moving backward with facing front by demolishing their nests and then build their nests again at the original (in both RB I and II) or near (in RB III) places. The removing behavior types above mentioned of both ant-lions of two species, Hagenomyia micans and Myrmeleon formicarius were compared each other. The results obtained are as follows.1) The ant-lions, larvae of Hagenomyia micans were divided into three types, A, B and C, according to their body size in this experiment. The larger their bodies are, the broader the limits of the size of the obstacles they can remove are.2) The larvae of Hagenomyia micans which can remove the obstacles from their nests show RB I, II and III when their nests have certain size.3) In the RB I of the larvae of Hagenomyia micans the ratio D/R of the removing distance D to the radius R of the original nest is almost constant.4) In the ant-lions of Hagenomyia micans the condition of sand making their nests i. e. higher or lower degree of homogeneity of sand particles has an important influence on their removing behavior. No matter whether the type of larvae is A or C, the removing behavior is observed more frequently in the latter than the former when the same obstacle is used in both the conditions of sand.5) When the nests have the same sand condition as that at their own habitats in both species i. e. Sa I in Hagenomyia micans and Sa VII in Myrmeleonformi carius, the removing behavior is observed much more frequently in the former than the latter. This suggests an important ecological significance in the nest building power of both species.