163 



Reply. — Yonr letter of July 25, with the accompanying specimens of mites, has 

 been forwarded to ns by special agent F. M. Webster, for reply. The mites are prob- 

 ably the species known as Tyroglyphus siro L., a species which, together with an 

 allied form T. longior, is frequently reported as infesting granaries and grocery .sup- 

 plies, such as cheese. Hour, and meal. Your account of their occurrence in your 

 warm-house is interesting, and it would seem that the measures you have taken to 

 rid the place should have been successful. If the warm house could have been 

 tightly closed, the fumes of burning sulphur maintained a sufficient time, ought to 

 have been effective in destroying the mites. The use of bisulphide of carbon would 

 have been attended with more satisfactory results. This substance will vaporize 

 readily and is a powerful insecticide, but very inflammable, and on that account care 

 should be taken in its use. Its disagreeable odor may be easily dispelled by thorough 

 airing. Where benzine can be used it will also prove an efficient means of destroy- 

 ing these pests. I can not understand why the mites should have been so numerous 

 and persistent in your case, unless they were repeatedly introduced with some of the 

 material (m^al, etc.) stored in the warm-house. I think that you will run no risk 

 in constructing an underground cellar on the spot formerly occupied by the warm- 

 house, if precautions are taken not to introduce mites with old meal or other ma- 

 terial. — [August 5, 1890.] 



A Beetle in Stramonium. 



I found these evidences of the ravages of the beetle you kindly described for me 

 at Mr. W. S. Thompson's drug store, 703 Fifteenth street, to-day. The stramonium 

 had been in a tightly closed can too.— [A. H. Hoehling, Washington, D. C, May 6, 

 1890. 



Reply. — The beetles which you sent from Mr. Thompson's drug store in stramo- 

 nium proved upon examination to be Sitodrepa panicea, well known to affect all sorts 

 of preserved drugs, — [July 5, 1890. 



The Pear-slug on Plum. 



I send you a box per express coutaining cuts from plum trees that are being de- 

 stroyed by an insect that is new to the foliage of this tree in this vicinity. I have 

 never before seen them. The effect is the same that is often seen on my rose-bush 

 foliage, but I think the enemy is not the same. The samples sent show the leaves 

 after the insect has finished the tree ; also the green leaves where they are now at 

 work. I have not been able to determine the origin, but evidently they come from 

 an egg laid. After the substance is all eaten from the leaf the insect is seen going to 

 the ground. Further than that I have not been able to trace them or find their de- 

 velopment. I hope to see a history of the enemy and its parentage and habits in 

 your valuable publication, Insect Life. An unusually cold, backward, and at times 

 wet season has seemed to diminish the usual quantity of most varieties of vegetable 

 enemies, except the cut-worm and white grub, which are rather more plenty than 

 usual. Twice spraying with Paris green has saved a fine crop of growing plums on 

 all the trees where fruit set after full blossom, but some trees with profusion of blos- 

 soms show no fruit at all. At full growth the worm is one-fourth of an inch long, 

 and under a glass looks like jelly, smooth and glossy, generally a dark stripe along 

 the back. I hope some may be alive, that you may see them under a more powerful 

 glass than I have. — [W. S. Wood, Shawano, Wis., June 23, 1890. 



Reply. — Your favor of the 23d inst. was duly received, accompanied with speci- 

 mens. You are right in believing that the larva on the plum is distinct from the 

 rose-slug. It is, however, closely allied to the rose-slug, and belongs with very lit- 

 tle doubt to the pear-tree slug (Eriocampa (Selandria) cerasi), the larva of which is 

 known to feed on pear, quince, and plum. The eggs are deposited by the parent 

 saw-fly early in June in little slits in the skin of the leaf. The young larvie soon 



