How insects behave 



shower would obliterate the pits and drown the larvae. Suitable places 

 are in the entrances of dry caves, under overhanging rocks and on the 

 verandahs of native huts that have an earthen floor. The community is 

 a drawback to the individuals, since the prey has to be shared among so 

 many, and sometimes the pits are so close together that its surprising 

 that any ants fall into them at all. 



A similar kind of community can be seen in the burrows of solitary 

 bees and wasps. These burrows are made in earth or soft sand, and are 

 often bunched together in communities for the same reasons as the 

 pits of the ant-lions, because suitable sites are limited in extent. 



A spectacular insect community is that of the New Zealand Glow- 

 Worm (Figs. 75, 76). This is not a tru£ glow-worm (which is a beetle), 

 but is a small fly, Arachnocampa luminosa, of the family Mycetophilidae. 

 The larva lives in communities in caves, surrounded by hanging threads 

 covered with a sticky material. The larvae are luminous, and attract 

 small insects, which are then trapped and devoured. In this instance 

 community life is beneficial to the individuals, because the combined 

 pattern of large numbers of larvae and filaments makes a better Hght- 

 trap for insects than a single larva could. 



Social Insects 



It is again a short step from Hving in a community of independent 

 individuals to Hving in a society, in which the individuals are dependent 

 on each other. The simplest social fife is maternal care of the young, and 

 signs of this can be seen in some insects which congregate for egg-laying, 

 and afterwards brood their eggs. 



The female of the horse-fly, Goniops chrysocoma, lays its eggs on a 

 leaf over water, and attaches itself to the leaf by means of its claws. In 

 this position it remains until the eggs are hatched, and ultimately dies, 

 still attached to the leaf. Rhagionid flies of the genus Atherix also 

 assemble in this way over their egg-batches on a leaf. The clusters of the 

 females of Atherix ibis that are occasionally found in Britain look like 

 swarms of bees. 



It used to be thought that as soon as the young larvae of Atherix had 

 hatched from the egg they fell into the water and lived independent 

 lives. Recent work has shown that in some species at least the tiny first 

 stage larva remains on the leaf and moults before taking to the water, so 

 that we have the rudiments of maternal care. 



Care of the young to this stage, or beyond, is shown also by earwigs 

 and by certain plant-bugs. 



95 



