HOUSEHOLD INSECTS 267 



more common than the former), the hornet, Vespa crabro, 

 and various species of ants. The wasps have so often 

 been described and are so common that we will pass them 

 over. Hornets, closely resembling big wasps with brown 

 markings in place of black, we may also leave out of con- 

 sideration and turn our attention for the moment to the 

 ants. Only one British species, Monomorium pharaonis, 

 frequents houses. It is a diminutive, red-coloured insect 

 which was imported into this country rather more than 

 eighty years ago, and even now has not spread everywhere 

 throughout Britain. So small is the insect that " seventeen 

 thousand individuals weigh one gramme, and it is probable 

 that the nest may contain millions of specimens." Like 

 the Argentine ant, this insect is social in its habits, and 

 the members of the community exhibit the same division 

 of labour. The workers are indefatigable in their search 

 for food, as every housekeeper who has experienced their 

 attacks can testify, sweet and fatty substances being 

 specially relished. 



SOME INJUKIOUS BEETLES 



It will be no surprise to learn that so large an order as 

 the Coleoptera, or beetles, supplies a number of household 

 insects, and that many of them are exceedingly destructive. 

 The most harmful are the beetles of wood-boring habit; 

 one species is described briefly in our chapter on " Insects 

 and Plants," and of the domestic wood-borers the commonest 

 is Anobium domesticum (fig. 72). This insect is of a 

 dark-brown colour and about one-sixth of an inch in length. 

 Within its burrows eggs are laid, and the white, curved, 

 fleshy, six-legged larvae rarely come to the surface of their 

 hiding-place. Nourishment is derived from the wood, 

 often of the oldest and dryest description, for, unlike the 

 larvae of Xyleborus dispar, these grubs have mouths well 

 adapted to such fare. Pupation takes place within the 



