INSECTS SPECIALLY LIABLE TO IMPORTATION. 7 



FLIES (DIPTEUA). 



Imported cabbage maggot. Chorlnphila (Pegomya) brasskx Bouchd. 



Seed-corn maggot. Chortopliila {Pegomya) fusciceps Zetterstedt. 



Grain gall midge. Contarinia tritici Kirby. (See Grains.) 



Hessian fly. Phytophaga destructor Say (May (tiola). (See Grains.) 



Pear gall midge. Contarinia pyrivora Riley. (See Pear.) 



Imported onion maggot. Chortophila (Pegomya) cepctorum Medde. 



Spinach leaf miner. Chortophila (Pegomya) hyoscyami LinniEUS (vicina Lintner). 



INSECTS SPECIALLY LIABLE TO IMPORTATION AT ANY 



TIME. 



There are certain groups of insects which are uniformly injurious 

 and can not therefore be given full justice in a bulletin of this type. 

 These insects should be especially guarded against and excluded on 

 general principles, whether incriminating evidence is found or not. 



TERMITES (TERMITID^). 



There have been several cases of introduction of termites into the United States, 

 notable among which was the importation of Leucotermes lucifugus Rossi in packing 

 boxes from Germany. The termites are uniformly injurious to wood and plant 

 growth and may be imported in any type of wood, whether in the form of nursery 

 stock, lumber, or manufactured product. A list of species is to be found in Wyts- 

 man's Genera Insectorum by Desneux (1903). 



THRIPS (THYSANOPTERA). 



The tiny fringe-winged thrips are very destructive to many crops, and should 

 always be guarded against. 



SCALE INSECTS (COCCIDiE). 



These tiny insects are inconspicuous and the greatest of care is necessary on the 

 part of inspectors to prevent their introduction. This family may be considered, as 

 a whole, a most undesirable group of insects. Many species have akeady been in- 

 troduced and become serious pests. Reference to Mrs. Fernald's Catalogue of Coc- 

 cidae as well as Technical Bulletins 12 and 16 of the Bureau of Entomology will 

 give full data as to literature. L. Lindinger, in his "Die Scliildlause (Coccidee)," 

 gives tables to the species of European scale insects attacking each plant. All names 

 of scale insects used in tliis bulletin have been verified by Mr. E. R. Sasscer. Several 

 genera of scales are illustrated on plates i-v to assist in determination. Some of the 

 species illustrated are not treated in the text, although congeneric species are. 



WHITE FLIES (ALEYRODID^E). 



The tiny white flies are very apt to slip in past even a zealous inspector. The 

 flattened scalelike larv;e of some species look so much like the plant tissue that they are 

 easily overlooked. The active little white-winged adults fly so quickly that rough 

 handling would tend merely to disperse them and increase the dangers of introduction. 

 Kirkaldy in 1907 issued a world checklist in Bulletin 2, Hawaii Board of Commis- 

 sioners Agriculture and Forestry. (See Technical Bull. 27, of the Bureau of Ento- 

 mology and Proc. U. S. Nat. Mus., No. 2156.) 



RED SPIDERS; MITES (ACARINA). 



These tiny eight-legged creatures are not insects, but so closely related that they 

 are generally treated as such. The red spiders are exceedingly minute and occur 

 on almost every type of vegetation. As their rate of multiplication is very rapid 



