Insect M'Kjrdlions in Tropical America. 155 



thousands past Guabito Station at a great speed, going 

 towards the east or south-east. About a quarter of an 

 hour later at a spot about half a mile north of the railway 

 station, and just over the border into Costa Rica, they 

 were flying due east in enormous numbers — 300 or 400 

 per minute on every 100-yards front. 



Nothing was seen of them agaui for over a month, but 

 in the interval I c[uestioned Mr. Ladd, a local amateur 

 naturalist, who said tliat he had frequently seen them, 

 that they oidy flew in the late afternoon and evening, and 

 that they changed the direction during the evening, flying at 

 Hrst in one direction and later all returning in the opposite. 

 Several other residents agreed as to the frequence of 

 their appearance, and a Mr. Weaver who lived several miles 

 north of Guabito at Paraiso, Costa Rica, said that they 

 always flew in the late afternoon and from north to south. 



On 10th May at 4.45 p.m. I again noticed them passing 

 the house three or four per minute in almost every direction, 

 but possibly more from north-east to south-west than 

 any other way. By G p.m. when it was getting dusk they 

 were still flying, and were possibly more common in a 

 reverse direction but not distinctly so. It was again 

 slightly cloudy after a hot day and no wind . Temperature 

 at G p.m. 78°' F. 



On 24th May they were again passing in the evening, with 

 a thinly clouded sky after a hot day with no wind . 



At 4.50 p.m. they were first noticed in numbers, almost 

 all going to the south or south-west past the house. At 

 5 p.m. very few were seen. At 5.5 another lot appeared, 

 this time going towards the north and north-west. From 

 5.40 to 6 they were passing in almost every direction, but 

 chiefly towards the north or towards the south. 



By 6 o'clock it was dusk, and the butterflies were difficult 

 to see except as shadows against the light. By lying on 

 my back on the ground I was able to count those passing 

 within my range of vision. In successive minutes 30, 48, 

 40, 33, 40, 35, and 32 were counted. " About equal 

 numbers going to the north-west and the south-oast, 

 but very few in any other direction.'-' At 6.30 it was 

 almost dark, and none were seen. 



Three more specimens were captured to-day. 

 The height of the flight was about three to twenty feet 

 above the ground and the speed was very great, at least 

 twenty miles an hour if not much more. It was sufficiently 



