674 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Senses of Ants.* — 0. C. Silverlock publishes the results of a series 

 of experiments carried on during the last two years with a view to 

 finding out whether ants are susceptible to the slight differences of 

 temperature between the different portions of the spectrum. He con- 

 cludes that ants are sensitive even to a rise of 0'?)° C. of temperature, 

 and that their appreciation of heat and cold is much more delicate than 

 our own. 



Insect Tree Pests.f — E. P. Felt describes the white-marked tussock 

 moth and the elm -leaf Iseetle, two leaf -feeders which cause very serious 

 damage to sliade trees, especially in cities and villages in New York 

 8tate. Both insects are fully described and figured, and an account is 

 given of their life-histories, their food-plants, their natural enemies ; and 

 remedial measures are suggested. 



New Parasitic Proctotrypid.J — A. ^X. Morrill describes a species, 

 believed to be new, of T'eJenomus {T. ashmeadi), which is parasitic on 

 the eggs of some insects, and especially on those of a Pentatomid 

 bug;, known as " conchuela," which is extremely destructive in the 

 Mexican cotton-fields. The great economic importance of the parasite 

 may be inferred from the fact that of 41 batches of Pentatomid eggs 

 collected, 36 were infested by the parasite and completely destroyed. 

 An interesting account of the habits and Ufe-history of the parasite is 

 given, and the probable relation between the occasional parthenogenesis 

 and the proportion of the sexes in the offspring is discussed. 



Mouth-parts of Ephemerid8e.§ — R. Sternfeld has studied the de- 

 generation of the mouth-parts and the change of function of the 

 intestine of the Ephemeridas, with special reference to their bearing on 

 the theory of descent. He finds that the degeneration of the mouth- 

 parts begins in the nymph stage, is externally complete in the sub-imago, 

 and quite complete in the imago. The individual organs do not undergo 

 equal degeneration, but the various genera do not differ much from one 

 another in this respect. There is no apparent connection between the 

 state of development of the larval mouth-parts in the different genera 

 and the degeneration in the imago. The intestine is not a rudimentary 

 structure. It is filled with air in the imago, and serves to increase the 

 power of flight and especially of soaring. This new function of the 

 intestine is of even greater biological importance than the one which is 

 lost, since it increases the adaptation of the short-lived insects for rapid 

 and certain pairing. 



Tracheal Gill-musculature in Ephemerid8e.]| — B, Diirken gives a 

 very full account not only of the tracheal gill-musculature but of the 

 body musculature in general. His facts are too numerous to summarise, 

 but it may be noted that he concludes there is no ground for homolo- 

 gising the gill and thoracic muscles, and in consequence tracheal gills 



* Nature Notes, xviii. (1907) pp. 165-9. 



t Bull. New York State IMuseum, cix. Entomology, 27 (1907) 14 pp., 8 pis. 



X Amer. Nat., xli. pp. 415-30 (1 fig.). 



§ Zool. Jahrb., xxiv. (1907) pp. 413-29 ( 1 pi. and 21 figs.). 



II Zeitschr. Wiss. Zool., Ixxxvii. (1907) pp. 435-550 (3 pis. and 30 figs.). 



