April, '21] DiETz: greenhouse inspection 193 



or caterpillars, in widely separated localities. We have noticed that 

 when any large grower and distributor has an outbreak of these two 

 pests it is not long before a number of the smaller growers who have 

 bought from the infested source have an outbreak. Hence, shall the 

 presence in a greenhouse of any of these insects mentioned, even though 

 they are being held in check successfully, warrant the withholding of a 

 certificate of inspection? 



The tropical ants are pests that seem to be gaining a foothold in our 

 northern greenhouses. One of our florists bought a large collection of 

 orchids from a jobber. With these he got the following insect pests, — 

 a hea\y infestation of Parlatoria pergandii Comst. on vandas, a heavy 

 infestation of Diaspis boisduvalii Sign, on cattleyas and a scattering 

 infestation of Coccus pseudohesperidum Ckll. and Targioma biformis 

 Ckll. (both new coccid records for Indiana) on the same host. But 

 what is probably m.ore im.portant than all these scale insects, he got a 

 heaA*}' infestation of the crazy ant — Prenolepis longicornis Latr. with 

 nests in the peat in which the orchids were growing. Just what^the 

 outcom.e of its introduction into this Indiana greenhouse will be, rem_ains 

 to be seen. What action should the state in which this shipment 

 originated have taken? And what action should the State of Indiana 

 take to prevent the further distribution of this insect? 



It is a common thing for Indiana florists to buy plants like aspidistra, 

 ficus, Dracena ivdivisa and Pandanus veitchii that have been grown out- 

 of-doors (or with slight protection in the winter) in the southern states. 

 I was amazed to find that the greenhouses where a large southern 

 distributor of aspidistras grew these plants were alive with the Argentine 

 ant. What action should be taken to prevent the spread of this insect, 

 northward ? 



Though comparatively little is known about greenhouse insects, 

 far less is known about most of the diseases attacking plants grown under 

 glass. There is carnation rust, the Fusarium root rot, and the Rhizoc- 

 tonia branch and stem rot on this host. There is the snapdragon rust 

 which has spread over the whole United States in the past twenty years. 

 The widespread distribution of this disease might at one time have been 

 checked. On roses we have such diseases as anthracnose and cane 

 blight. There are doubtless many others which will attract attention 

 following intensive study. Should the presence of any of the diseases 

 mentioned in a greenhouse warrant the withholding of a certificate of 

 inspection ? Can infected plants be sent under a qualified certificate of 

 inspection? Are these diseases dangerously injurious? 



At present, three alternatives are open to state inspectors relative to 

 plants grown under glass. The first is to let any and all persons who 



