1272 Insects. 



wards the higher parts of the slope. And herein I imagine that I re- 

 cognize a beautiful instance of natural instinct, both in the butterfly 

 and caterpillar : the former deposits its eggs low down the declivity, 

 where the young brood may rest most securely sheltered and least ex- 

 posed to the wintry storms, but when the caterpillars are sufficiently 

 advanced in growth, they ascend to the higher parts of the steep to 

 feed and undergo their transformation : were the chrysalis formed 

 below, they would probably have too much moisture and too little sun ; 

 whereas by being formed higher up they have a sufficiency of both to 

 bring them to maturity. 



This butterfly is single-brooded ; but there is a succession of them, 

 varying in duration according to the season. The earliest dates on 

 which I have met with it is May 1st, the latest in July ; but in the 

 latter case the specimens were bred in captivity. I never remember to 

 have seen it so late in the state of liberty ; not later indeed than the 

 middle of June here. They are very difficult to rear from the larvae, 

 and those that I have bred, are not only disclosed much later than in 

 the state of freedom, but are not nearly so fine and perfect. They in 

 general fly slowly and peacefully, except when alarmed, gliding gently 

 from flower to flower. I have taken as many as two dozen without 

 moving from the spot where I stood, as they successively visited the 

 stems of the grasses round me. 



This Fritillary was much less plentiful last season than heretofore ; 

 and in some of its former haunts has quite disappeared. It has many 

 foes : for besides the march of improvement in cultivation which gra- 

 dually invades its haunts, the same natural causes which promote its 

 abundance, also multiply its enemies. Silpha obscura and tristis de- 

 stroy the larvae : and a large ground spider, very numerous in the 

 spots which it frequents, feeds on the perfect insect ; it lies in wait 

 till the butterfly alights upon the low plants, or on the ground, then 

 rushing forward, seizes it by the neck, and holds it captive with such 

 tenacity, that both insects may almost be pulled in pieces, ere it will 

 relax its grasp. 



J. F. Dawson. 

 Ventnor, January 12th, 1846. 



Migration of Butterflies. — By the assistance of friends and correspondents in dif- 

 ferent parts of the island, we have been enabled to trace the course taken by the white 

 and yellow butterflies in their annual migration. They were seen crossing the Kandian 

 mountains all in the same direction, varying slightly from south-west, and simulta- 



