June, '21] SWEZEY: HAWAIIAN INSECT IMMIGRANTS 255 



rived a long, long time ago. Immigration, however, is a process that 

 has continued thru the intervening time, even to the present. Many- 

 species of insects have arrived and become estabHshed in modern 

 times, and have not yet changed so as to become peculiar to the Ha- 

 waiian Islands, but have a wide distribution to other Pacific Islands 

 or to the continental shores of the Pacific. Much of the insect favina 

 of the lowlands in Hawaii is made up of such widely distributed species. 



Then more recently has been the immigration in connection with 

 human enterprises, the coming of insects in various ways thru com- 

 merce, as chance wanderers on ships, or as insect pests infesting plants, 

 fruits, or various other foods and articles of commerce. In the latter 

 way, many cosmopolitan pests had become established in Hawaii long 

 before there were any attempts made to prevent it by means of quar- 

 antine inspection or other means. 



For about twenty years very efficient quarantine practices have been 

 in effect at the port of Honolulu, and many kinds of insect pests are 

 thus intercepted which might be of serious importance should they 

 gain entrance and become established. This constant vigilance does 

 not entirely check insect immigration, however, and we are annually 

 finding more new arrivals, most of which are of no importance, some 

 are beneficial, and an occasional one proves to be injurious. 



Some of the insect immigrants that have been noted most recently 

 (1919 and 1920) are here given with notes as to distribution, habits, 

 importance, etc. Many of the smaller ones no doubt have been pres- 

 ent for several years and escaped notice. Unless stated otherwise, 

 they were first observed in Honolulu. 



Hymenoptera 



Megachile sp. [Apidae] 



Specimens of this hitherto unknown bee were first captured at Mokapu, Oahu, 

 September, 1920. None have been taken elsewhere as yet. 

 Vespa occidentalis Cresson. [Vespidae] 



This American wasp was first recorded from a single female taken at Halemanu, 

 Kauai, at an elevation of 3500 feet, by Mr. H. P. Agee, January 30, 1920. Later 

 Mr. J. A. Kusche reported to have seen it abundant in the same region of Kauai in 

 April, 1919. It has not been seen anywhere else in the Islands yet. It is very 

 strange that this insect should become established first in the midst of mountain 

 forests. 

 Silaon rohweri Bridwell. [vSphecidae] 



This wasp was first reported in May, 1919, from the coast at Waianae on the 

 west side of Oahu. In August, 1919, it was found at Ewa on the southwest part 

 of Oahu, and in August 1920 was found in Honolulu. This tiny little wasp stores 

 up nymphs of a bug (Nysius sp.). It is considered as an immigrant, possibly from 

 Central America or Mexico. / 



