INSECTS. 91 



since the discovery. The butterflies are not especially striking to the 

 casual observer. Among them is the widely spread tawny-colored 

 milkweed butterfly, Anosia plexippus Fabr., which has found its way to 

 Guam, together with the introduced Aselepias curassavica, on which 

 its larva feeds. Both the plant and the insect, although of American 

 origin, now occur on many islands of the Pacific Ocean. Among the 

 night-flying lepidoptera there is a large sphinx moth (Protoparce celeus 

 Hbrt.), the larva of which feeds on the tobacco plant and resembles 

 very closely the tobacco worms of America. It is possible that this 

 insect may have lived on the island before the introduction of tobacco, 

 feeding upon some solanaceous plant, but it is probable that it came to 

 Guam with the tobacco. Possibly its eggs were brought on dried 

 leaves of the plant. Among the other pests introduced b}^ the 

 foreigner are clothes moths {Tinea pellionella L.). In the zoology of 

 the Freycinet expedition several butterflies collected in Guam, includ- 

 ing an Argynnis and two species of Danai's, were described as new. 



Among the h}mienoptera there are several interesting species of 

 wasps and ants. One wasp, probably a species of Polistes (P. hebraeus 

 Fabr. ?), is social in its habits. During the greater part of the year 

 it frequents open fields, building its nests in bushes a foot or two 

 from the ground, attaching them to a limb by a peduncle with the 

 mouth of the cells pointed downward, and not covered by a papeiy 

 wall, as in our hornets' nests. In these cells the eggs are laid and 

 the larvae are fed. When about to undergo transformation the 

 larvae spin a covering which seals up the cell. The males differ 

 from the female in appearance and are stingless. Besides the males 

 and perfect females there are workers. Both the females and the 

 workers sting, but their sting is not very severe. These insects 

 are very abundant all over the island, especially in abandoned clear- 

 ings grown up to guavas and other low bushes. It is almost impos- 

 sible to cross such a field without stirring up a nest or two, and 

 one of the commonest occurrences on an excursion is to hear a loud 

 outcry on the part of 3 r our guide, whose naked legs are covered 

 with the stings of the "sasata," as they are called. . In revenge he 

 usually finds a dry leaf of a coconut, which he converts into a torch 

 and burns the nest. These wasps are not very pugnacious, and will 

 only sting when they think their nest is attacked. After it has been 

 burned they fly round and round the place without attemptiug to take 

 vengeance. In the winter time (the month of December) they flock 

 into houses in great numbers and settle upon some prominent point 

 on the ceiling or on a chandelier, clinging together in masses like 

 swarming bees. There they remain for a month or two in a state of 

 torpidity. They are disagreeable guests, as they have a habit of drop- 

 ping to the floor from time to time, and it is not unusual on getting out 

 of bed in the morning to step on one of them, too stupid to fry but 



