CHAPTER V 



NATURAL HISTORY WORK IN CARTAGO 



One of the chief objects of our expedition being the study 

 of the living dragonflies or Odonata, and of their larvae, 

 we very soon began to rear at Cartago such eggs and larvse 

 as we could procure. Eggs were obtained from the Zygop- 

 terous species (those having wings of equal width, often called 

 damsel flies) by bringing home and keeping in homeopathic 

 vials the plant tissues in which we had seen the female 

 insert her eggs. The Anisopterous dragonflies (or those 

 having the hind wings wider than the fore wings) could often 

 be induced to oviposit if we dipped the tip of the abdomen 

 repeatedly into water in a vial. When the eggs in these 

 vials hatched, as they usually did sooner or later, the young 

 larvae were watched, drawings of several of the early stages 

 were made from life, in many cases under the binocular 

 microscope and some individuals of each stage, with exuviae, 

 preserved for future study. Larger larvae, which were 

 collected either near Cartago or brought there from other 

 places, were kept in glass jars, tumblers, or bottles for ob- 

 servation. Most of these larvae were kept one in a bottle, 

 for the practical reason that if they did not start one in a 

 bottle they quickly became so. There were a few exceptions 

 to this rule. Thaiimatoneura larvae, for instance, are slug- 

 gish and not aggressive, and if the difference in size be not 

 too great can be safely kept together but in general it is 

 dangerous to attempt it. Each larva had a stick, branch, 

 clump of water weed or small bromeliad for a resting place, 

 and we soon found it was desirable to allow the stick to pro- 



