HARDWICKE'S S CIE NCE-GO SSIF. 



121 



GRAPHIC MICROSCOPY.: 



By E. T. D. 



No. VI. — Pupa of Locust, One Day Old. 



HE " Complete 

 metamorphosis " 

 of an insect con- 

 veys the idea of a 

 sequence, starting 

 from an egg, pro- 

 ducing an apodal 

 caterpillar, or 

 maggot (the larval 

 feeding state, 

 when the chief bu- 

 siness of life is per- 

 formed), leading 

 to the chrysalid, 

 a period of repose, 

 requiring no food, 

 eventually break- 

 ing or bursting 

 into the imago, 

 the perfect insect 

 — a serial transition from a simple and elementary 

 condition, to one complex and compound. 



In the Orthoptera (the order comprising the locusts) 

 and in the Hemiptera (bugs, plant-lice), the true 

 apodal larval state is masked, the vermiform condition 

 being developed in the egg — thus, the young Orthop- 

 teran and Hemipteran issues at once into actual life, 

 with perfectly developed jointed legs, eyes, antennae, 

 and maxillary organs. The metamorphosis the 

 Locust undergoes from the potential germ to the 

 procreative imago, may be as varied in order as that 

 of the butterfly, but the initiative, and more im- 

 portant changes occur in the egg, which, when 

 hatched, assumes not a larval appearance, as generally 

 understood, but the exact likeness and habits of its 

 parents ; this active pupa or nymph, by successive 

 moults, attains a stage when the wings expand to 

 their full size, the circulation of the blood through 

 the nervures is arrested, and the development per- 

 fected. 



It is clear that the pupa stage, which, in the butter- 

 fly is passive and embryonic, is, in the locust, active 

 No, 234.— June 1884. 



and voracious, whilst the condition of the larval 

 state is reversed ; the egg, when hatched, reveals a 

 creature not only in the semblance of the perfect 

 insect, with similar instincts, desiring and capable of 

 obtaining the same food ; but so far superior in 

 development to what is popularly understood as a 

 larva, or even a pupa, as to be able to perform every 

 function of the mature condition, except flight, the 

 wings and their cases only bursting through the 

 thoracic rings after the second moult. It seems, 

 therefore, a matter of mere nomenclature whether it 

 should be designated larva (a ghost), or pupa (a doll), 

 the plate representing a locust one day emerged from 

 the egg, at once suggests an intermingling of both 

 characters. It has been named " Pupa." 



Burmeister, ignoring the term larva, designates 

 this condition of the winged genera of the orders 

 Orthoptera and Hemiptera "sub-incomplete pupae," 

 and Lamarck, in describing this tenacity of similarity 

 of the insect in its progress Irom the egg to per- 

 fection, adopts the term " nymphse." The familiar 

 cockroach (Blatta) of the same order may be seen 

 from the moment of emerging from the egg, in all 

 stages of growth, with all its parents' well-known 

 social domestic qualities, powers of appetite, and 

 activity. 



The Orthoptera although by no means an ex- 

 tensive Order, either as to genus or species, is of very 

 general distribution ; representatives of the genera 

 Gryllus (grasshoppers) and Acheta (crickets) are 

 found in most countries. Loatsta cruciata, genus 

 Oidipoda, mostly exotic, is the familiar locust of the 

 East, and of tradition ; its powers of increase and 

 devastation are matters of history and common know- 

 ledge. The eggs are deposited in cases or tubes of 

 earth about an inch and a half deep, previously made 

 by the female, softening the material with a watery 

 glutinous secretion ; each tube holds fifty to sixty 

 eggs, they are always placed in hilly country, and 

 invariably in uncultivated soil. It is said, by an 

 actual observer, that when depositing the eggs, the 

 female receives a certain homage or attention, being, 



G 



