226 Benj. D. Walsh on the Insects inhabiting the Galls 



potato-like type, and bred from them, April 16 — 21, 33 9 without a 

 single % among them, which differ in no wise from 9 9 bred from 

 galls found on S. humilis. I observe that in this species there is an 

 indistinct whitish-cinereous very narrow orbit behind the eye, repre- 

 senting the broader and very conspicuous white orbit found in the 

 inquilinous Cec. orbitalis Walsh. From these S. discolor galls I also 

 bred the Decatoma reared in such abundance from the S. hu- 

 milis galls. 



No. 13. GrALL S. verruca Walsh. — Oct. 11th I found several of 

 these galls on S. discolor, undistinguishable from those found on the 

 closely allied S. humilis. The larva was orange-color with the usual 

 whitish bowel-like markings, .08 inch long, 2 J — 3 times as long as 

 wide, depressed, with a large head. Breast-bone black, elongate-semi- 

 oval and rather longer than wide. Two specimens. Thus we have no 

 less than 4 species of Cecidomyidous galls common to the two closely- 

 allied Willows, S. discolor and S. humilis, viz : S. gnaphalioides, S. 

 siliqua, S. batatas and S. verruca. 



No. 14. GrALL S. semen Walsh. — This is not a Cecidomyidous, but an 

 Acaridous gall, and is constructed on the same principle as 15 or 16 

 others with which I have become acquainted, all growing on the upper 

 side for the most part of the leaf of various trees, and composed of a 

 more or less elongate sack opening below by a more or less closed aper- 

 ture, and on its interior surface covered with rough excrescences of dif- 

 ferent shapes On the other hand, all Cecidomyidous galls known to 

 me are smooth and free from excrescences inside. From most of these 

 Acaridous galls the mites escape through the aperture below, but in 

 some, e. g. Cerasi crumena Walsh MS, on Cerasus serotina, the gall 

 always bursts open above as in Salicis semen. Similar, but not iden- 

 tical, galls are found on several other Willows. On Aug. 25 I found 

 in one of these S. semen galls, which was about .03 inch in diameter, 

 as many as 40 or 50 hyaline-whitish young Acarus, which, as is usual, 

 were much more elongate than the perfect Mite. Hence it may be 

 readily understood how minute their size is, and how liable they are 

 to be overlooked, except under a very powerful lens, especially as, un- 

 like the perfect Mite, they are very dull and sluggish in their motions, 

 which indeed seems to be the universal rule with all the larvge of the 

 (Jail-making Mites. The perfect Mite, which was found 011 the same day 

 in other galls, is hyaline-whitish with antenuifbrm front legs as long 

 as its other legs, which front legs it elevates in the air and constantly 

 vibrates up and down as it runs. Those found in galls on other trees 



