132 Invert cbrata. 



Other beetles are found in articles of food, such as 

 Tenebrio, the meal-worm often found in ships' biscuits, 

 FlG ?6 Dermestes, or the bacon 



grub; others are the pests 

 of museums, like the little 

 Anthrenus or Ptinus the 

 herbarium beetle, and 



The blistering \*<X\e(Canthans PtiUmiS, the bookworm. 

 vesicatoria). ^ few afe temporar y para . 



sites; thus the larva of Rhipidius lives in the abdomen 

 of the cockroach. Some beetles are luminous, such 

 as the glowworm and the firefly. 



Some beetles emit an ammoniacal smell when irri- 

 tated ; others, like Meloe, secrete a drop of acrid oil 

 under the same circumstances. This secretion renders 

 the bodies of some of them useful in medicine for 

 blistering purposes ; thus the bodies of Cantharis vesi- 

 catoria (fig. 76) are the Spanish or blistering flies of 

 commerce. Some species of beetles inhabit caves 

 and are eyeless; others are aquatic and fitted for 

 swimming. The sizes of beetles are also exceedingly 

 variable ; some, like the large Hercules beetle, being 

 nearly six inches long, while others are of microscopic 

 dimension. The antennae are of very variable shapes 

 and sizes, being in some much longer than the body, 

 in others very short and inconspicuous ; in some, like 

 the common cockchafer, lamellar, in others stag-horn- 

 shaped, &c. 



ORDER XIII. Hymenoptera (membrane-winged) 

 includes bees, wasps and ants, and in these the com- 

 plexity and intelligence of the class culminates. They 

 are characterised by having four naked membranous 



