131 



the plants from their origmal container. As a result of these experi- 

 ments the Federal Horticultural Board requires that all plants fumi- 

 gated in the original container must be fumigated with 1 oz. of sodium 

 cyanide with an exposure of one hour. A preliminary vacuum of 

 20 inches is required prior to the generation of the gas. To determine 

 the penetration of hydrocyanic-acid gas under vacuum conditions 

 experiments were made with Datana integerrima, G. & R. (black- 

 walnut caterpillar). The results of fumigation experiments are given 

 in tabulated form. It was found that where excessive dosages are 

 not employed, orchids are apparently stimulated by hydrocyanic-acid 

 gas. Infested orchids at the time of arrival at the port of entry, 

 if in a reasonably good condition, are not seriously affected by hydro- 

 cyanic acid gas generated at the rate of 1 oz. sodium cyanide per 

 100 cu. ft. and are not killed where a 4 oz. dosage is used. Insects 

 that are not hermetically sealed in stems or pseudobulbs of Cattleya 

 can be killed in the original cases with hydrocyanic-acid gas provided 

 a 20-inch vacuum is previously effected. 



Van Zwaluwenburg (R. H.). Report of the Entomologist. — Rept. 

 Porto Rico Agric. Expt. Sta., 1917 ; Washington, D.C., 20th Sep- 

 tember 1918, pp. 31-34. [Received 17th January, 1919.] 



Much of the maize grown in Porto Rico fails to produce seed, and 

 during 1917 the larvae of an undetermined Phorid fly has been 

 suspected of causing this damage. The eggs of this fly are laid in 

 clusters of 25 or more among the strands of the new silk, several such 

 clusters frequently being placed in the tuft of a single ear. The 

 larvae upon emerging from the egg feed on the silk strands, following 

 them downwards. All of the strands may be destroyed in this 

 manner before the silk has been pollinated and as a result very little 

 seed is produced. The work of the larvae also attracts scavenger 

 beetles such as Carpophilus sp. and doubtless encourages fungus infec- 

 tion. In June over 75 per cent, of the ears in a field at the Station 

 were found either infested with larvae or with eggs in the silk tuft. 

 The fly is obviously a primary pest and not a scavenger. A Capsid 

 bug was observed to be fairly abundant and to feed upon the eggs 

 of the fly. Investigations are being continued with regard to this 

 pest. 



The larvae of a Noctuid moth, Noropsishieroglyphiai, feed commonly 

 on the foliage of Waltheria americana and have also been reared upon 

 Morongia leptoclada. The larvae are gregarious and drop to the 

 ground if disturbed. The oval pupa-case is formed on the stem of 

 the food-plant and covered by grass and bits of leaves. 



A heavy infestaton of Anastrepha fraterculus (mango fruit-fly) 

 occurred in July in fruits of Eugenia jambos. This is the first record 

 of this plant as a host of the fly in Porto Rico. The scale, Conchaspis 

 angraeci, is one of the few insects observed upon vanilla, which has 

 only recently been cultivated in the Island ; it does not, however, 

 seem likely to become an important pest. A local outbreak of a 

 Noctuid moth, Melipotis jannaris, occurred in June on guama {Inga 

 laurina) ; a few days after the appearance of the larvae they had 

 all entered the ground to pupate. Some protection against Strategvs 



