1*2 IN THE GUIANA FOREST. 



the river Essequebo for nine miles. As far as we 

 have seen all are males, and it may be presumed 

 that they are off in search of mates. But we 

 cannot find that there is a dearth of females at 

 any particular spot ; they are common enough in 

 Guiana, and when larvae are bred the sexes are 

 about equal. We do not suggest that the flight is 

 one long journey from the West Indies to Patagonia, 

 but rather that flocks gather at some place and 

 proceed in a southerly direction for long distances, 

 where they probably disperse. Great numbers are 

 lost at sea, and this no doubt prevents what might 

 be a serious increase. At present, however, they 

 are not pests to economic plants. 



The family which has been most successful in 

 becoming immune to poisons is the Sphingidae, or 

 hawk-moths. Very few of these feed on what we 

 should consider harmless vegetables ; some are, 

 however, pests to the grape vine. Their ravages 

 on certain plants are very destructive, the principal 

 natural order being the Solanaceae, and here a 

 single species will feed on Solanums, including the 

 tomato and capsicum, tobacco, Datura and Physalis, 

 but not go outside the natural order. Other species 

 feed on Apocynaceae and Euphorbiaceae, both 

 highly poisonous families. The damage effected 

 by a few larvae is enormous ; the growers of tobacco 



