December 25, 1895.] 



Garden and Forest. 



513 



Scale Insects Liable to be Introduced into the 

 United States. 



ABOUT 140 species of scale insects are now known from 

 the United States, of which, however, at least thirty- 

 five have certainly been introduced through human agenc)\ 

 The following are noticeably injurious : 



(i) Probably or certainly introduced. Icerya purchasi, 

 Gossyparia ulmi, Dactylopius adonidum, D. citri, Orthezia 

 insignis, Asterolecanium c]uercicola, Pollinia poUini, Leca- 

 nium persicas, L. juglandis, L. hemisphaiTicum, L. oleae, 

 Aspidiotus nerii, A. ficus, A. aurantii, IVIytilaspis citricola, 

 M, gloverii, M. pomorum, Aspidiotus perniciosus, Chio- 

 naspis citri, C. biclavis, Aulacaspis rosa^-, Diaspis amygdali, 

 Phenacoccus aceris, I.ecanium hesperidum, Parlatoria per- 

 gandii. 



(2) Probably or certainly native. Pulvinaria innumera- 

 bilis, Lecanium pruinosum, L, ribis, L. tulipiferas, L. fitchii, 

 Aspidiotus uva;, A. ancylus, A. juglans-regise, Chionaspis 

 furfurus, C. ortholobis, Aspidiotus rapa.v. The second and 

 the last have, perhaps, been introduced. 



Thus it is seen that most of the mjurious species have 

 been introduced into the country ; in fact, all of those 

 which are of first importance, if we, perhaps, except Chio- 

 naspis furfurus and Pulvinaria innumerabilis. It is just 

 |30ssible that Aspidiotus perniciosus is native. Just lately, 

 Asterolecanium pustulans has turned up in Florida, and 

 Dactylopius virgatus in Texas. These species are not yet 

 complained of in the United States, but both are very 

 injurious in certain tropical localities, such as Jamaica, 



In tlie great majority of cases it is not known exactly 

 how or when the introduced species reached this country, 

 but it may be broadly stated that they all came on plants. 

 Positive evidence is, however, afforded by Mr. Alexander 

 Craw, the energetic horticultural quarantine officer of Cali- 

 fornia. He boards the steamers that arrive at San Fran- 

 cisco, and inspects all plants and trees about to be landed. 

 Quite frequently he finds them infested with scale insects, 

 and in all such cases has them destroyed, being empow- 

 ered by the law of the state to do so. The labors of Mr. 

 Craw have probably not been appreciated at their true 

 value ; in fact, it is impossible that they should have been, 

 because the most remarkable results he has achieved have 

 not yet been published. Unfortunately, we possess no 

 detailed or accurate information regarding his earlier finds, 

 but recently he has been sending me the species defected, 

 and without naming them here I may say there were seven 

 on plants from Japan, three from Honolulu, two each on 

 plants from Mexico and Central America, and one each on 

 plants from Tahiti, the Marquesas Islands and Australia. 



Not a single one of these scale insects is native to this 

 country, and only one, Aspidiotus aurantii, is established 

 in California. Some of them, Diaspis amygdali, for exam- 

 ple, are known to be very injurious. Yet these results 

 have all been obtained quite recently ; m fact, every month 

 seems to make remarkable additions to the list. Let the 

 California people consider what it would have been worth 

 to them to have kept Icerya and the San Jose scale out of 

 the country ; let them novi' consider, in view of recent 

 experiences in the east, what it would be worth to keep 

 Diaspis amygdali (lanatus) out. The damage done by 

 either of these species in a few years would exceed the 

 salary of a dozen quarantine officers. 



It is hardly sufficient to say that California is pursuing a 

 wise policy in this matter ; to do otherwise, with the inter- 

 ests she has at stake, would be sheer imbecility. In view 

 of all this, it seems amazing that nothing in the same way 

 is being done in the east or south. I do not propose at 

 the present time to discuss the question of quarantine along 

 the Atlantic seaboard, but rather to call attention to the 

 condition of affairs in the south. From California to Florida 

 there is no serious attempt made of any kind to prevent the 

 introduction of pernicious insects. 



From the regions south of the United States (Central and 

 South America and the West Indies) are known at present 



about 130 species — that is, not quite so many as from the 

 United States. But there can be no doubt that the tropics 

 of America are very rich in scale insects, and the reason 

 why no more are recorded there is simply that, except in 

 the West Indies, very little collecting has been done. 



To illustrate the abundance of scale, insects in the tropics 

 I may say that I found in the small garden attached to Dr. 

 Strachan's house, in Kingston, Jamaica, July 27th, 1892, six- 

 teen species and varieties, seven of which have never been 

 found in the United States. It is true that one of them, the 

 species Parlatoria pergandei, occurs in our country, but 

 the variety Crotonis, which I found, has an entirely differ- 

 ent food-plant, and from an economic point of view is 

 quite a different thing. Perhaps the most pernicious spe- 

 cies among the sixteen not found in the United States 

 is Aspidiotus articulatus, which attacks Citrus-trees as the 

 red scale does in California. 



To give anything like a list of the scale insects in the 

 West Indies whicli are liable to be imported into this coun- 

 try would occupy too much space. But there are specially 

 dangerous ones infesting Citrus-trees, Sugar Cane, Sweet 

 Potato, Yam, Cotton, Palm, Hibiscus, Acalypha and other 

 plants which are articles of common transportation. 



As regards Mexico and Central .\merica our knowledge 

 is singularly deficient, and would tie fragmentary, indeed, 

 had not Professor C. H. T. Townsend lately been collect- 

 ing in Mexico for the Department of Agriculture. The 

 results of his mission will be set forth in a bulletin shortly 

 to be published ; but it may be permissible to state now 

 that he found, in particular, several injurious scale insects 

 upon the Citrus-trees. One of these, Aspidiotus scutiformis, 

 has never yet been detected in the United States. Thus 

 we are threatened all along our southern border, and 

 the process of introducing injurious species, which has 

 gone on so far almost unheeded, is likely to lead to conse- 

 quences more serious than are often contemplated. It is 

 true that the climatic differences, from south to north, afford 

 a certain amount of protection, but the way in which the 

 Diaspis amygdali (lanatus), of the West Indies, has estab- 

 lished itself in the city of Washington should convince any 

 one that immunity from differences in climate cannot be 

 relied upon. Nobody supposes that many West Indian 

 species could establish themselves far north in the United 

 States, but many are already common to the tropics and 

 the southern states, while trouble may even be caused in 

 the north in hot-houses, as with the mealy bugs and Orthezia 

 insignis. It is not necessary to postulate that the Coccids 

 should destroy whole crops, in order to make out a case for 

 preventive measures. The profit usually represents but a 

 small part of the value of the crop, and the insect has but 

 to eat that up to ruin the business. Thus any loss will be 

 felt, unless, perhaps, in times of so-called overproduction. 



It is useless to cry out after the harm is done ; now is 

 the time; in a (ew years it will be too late, as indeed it is 

 already too late to stop many species. The indications 

 from the facts at hand are plain. In the first place, strenu- 

 ous efforts should be made to ascertain more accurately 

 the Coccid fauna of the whole neotropical region, and 

 especially of those parts near our own borders. In the 

 second, quarantine should be set up, as in California, at 

 those places through which plants are brought into the 

 United States. These are not numerous, and probably it 

 could be made unprofitable for importers to bring their 

 plants through ports not quarantined ; that is to say, if the 

 trade would recognize that no plants could be safely re- 

 ceived unless certified as clean by the appointed quarantine 

 officer, non-inspected plants would lose some of their 

 value, even if salable. „, „ , ,, , „ 



Las Ciuces, N. M. J- JJ--I- Lockcrell. 



Tlie clement of interest whicli, beyond question, should be 

 placed first, if possil)le, in the park of any great city is that of 

 an antithesis lo its l)ustling, paved, rectangular, wallod-in 

 streets — a requirement best niet by a largo meadowy ground 

 of an open, free, tranquil character. — Ohiis/cii &-' Van. v. 



