30d PERIPATUS, MYRI0P0DS, AND INSECTS. 



does not take place, and the eggs in consequence are parthenogenetic. 

 Queens which have never mated, or which have exhausted their stock 

 of male elements, habitually lay drone eggs, but those which are laying 

 abundant fertilised eggs at times also lay unfertilised eggs. This with- 

 holding of spermatozoa is said to be "voluntary," and related to the 

 needs of the colony, but the physiological reason is unknown. 



The workers possess female organs similar in type to those of the 

 queen, but of an extremely rudimentary nature. 



The eggs are laid singly in the cells of the comb, at the rate of about 

 two per minute, for weeks together. They are of the usual insect type. 

 According to the size of the cell in which it is deposited, and the food 

 with which it is furnished, the fertilised ovum 

 develops into a worker or into a queen. The 

 development takes place within the cell, and 

 includes a complete metamorphosis. 



Classification of Insects. 



I. Primitive wingless insects, Apterygota or 

 Aptera, including Thysanura, e.g. Cam- 

 podea, Lepisma ; Collembola ; Spring- 

 tails, e.g. Podura, Smynthtirus. 



II. Winged insects, Pterygota (in some degen- 

 erate forms the wings have been lost). 

 A. With mouth-parts usually adapted 

 throughout life for biting (Meno- 

 gnathous), with no metamorphosis 

 (Ametabolic) or with incomplete 

 metamorphosis (Hemimetabolic). 

 e.g. Orthoptera (cockroach, 

 locust, cricket, etc. ) ; 

 CoiTodentia (Termites, 

 bird - bee) ; Odonata 

 (Dragon - flies) ; Eph- 

 emerida (May-flies) ; 

 and Dermaptera (Ear- 

 wigs). 

 With mouth-parts adapted in the main as suctorial organs 

 (Menorhynchous), usually with no metamorphosis (Amet- 

 abolic). 



e.g. Rhynchota or Hemiptera, e.g. Phylloxera, aphides, 

 coccus insects ; Cicadas ; bugs ; water-scor- 

 pions, lice. 

 With complete metamorphosis (Holometabolic), with 

 mouth-parts always adapted for biting (Menognathous), 

 or adapted at first for biting and afterwards for sucking 

 (Metagnathous). 

 e.g. Coleoptera (beetles) ; Diptera (two-winged flies) ; 

 Lepidoptera (butterflies and moths) ; Hymen- 

 optera (ants, bees, and wasps). 



Fig. 133. — One of 

 the Thysanura 

 {Campodea staphy- 

 linus). — After 

 Lubbock. 



The hairs and bristles 

 have been removed. 



