THE OVIPOSITION RESPONSE OF INSECTS 7 



importance to the potato tuber moth (Pthorlmaea operculella). 

 In France, Picard (58) states that it generally lays its eggs in the 

 cavities which surround the buds on the surface of the tuber, 

 in incisions of the skin, or on the clumps of dried earth which 

 adhere to the surface. It will also oviposit on the foliage of Ver- 

 bascimi and Cynoglossum which is felted and plaited, in preference 

 to that of Linaria, for although the latter is more closely allied to the 

 Solanaceae than Cynoglossum, its leaves have smooth surfaces. In 

 laboratory experiments, the moths often laid a part of their eggs 

 on the muslin sides of the cage, even when potatoes were available, 

 but eggs were placed only exceptionally on the glass walls. Graf 

 (29), who has studied the potato tuber moth in America, likewise 

 reached the conclusion that oviposition was stimulated by rough- 

 ened surfaces. The Angoumois grain moth (Sitotroga cerealella 

 Oliv.) does not require the presence of grain as a stimulant for 

 egg laying, but, in captivity, will readily oviposit between strips 

 of cardboard. Usually all the eggs are deposited in the crevice be- 

 tween the strips (75). Dewitz (20, 22), while pointing out the 

 possible role of odor in the attraction of the gravid female of 

 Gochylis ambic/ueUa, also states that oviposition on the grapevine 

 bud may be attributed to a contact stimulation. In another paper 

 (21 p. 233) he quotes Marchal to the effect that the female of 

 Polychosis botrana is guided during oviposition upon the smooth 

 surface of the grape by the tactile power of the abdomen. Ovipo- 

 sition would not take place on grapes covered experimentally with 

 powder or a sticky mass. The experiments of Adolph (1) on 

 Drosophila melanog aster show that the texture of the substance with 

 which the gravid female comes in contact exercises a marked effect 

 upon the quantity of eggs laid. Boiled agar was more potent in 

 this respect than any of the solutions which were used to test the 

 effect of taste, odor, or a combination of taste and odor. The 

 character of the nidus also has a very evident influence upon the 

 oviposition of the house fly (Musca domestica) . Under appropriate 

 conditions, pine sawdust is considerably less attractive than timothy 

 chaff or horse manure, and moist absorbent cotton (containing 

 ammonium carbonate only) was oviposited upon only once in 11 ex- 

 periments (63, 64). Some observations by Picard (60) on the ovi- 

 position of Pimpla instigator F., a hymenopterous parasite of the 

 chrysalis of Pieris brccssicae L., and of certain other Lepidoptera, 

 are interesting in this connection. If an old chrysalis shell or a 

 cylinder of white paper is coated with fresh blood from a chrysalis 

 of Pieris, the parasite will pierce it with its ovipositor. The stimu- 

 lus is olfactory, but according to Picard the actual deposition of 

 egg depends upon a tactile stimulus produced by the resistance 

 of the living tissue within the chrysalis. Indeed, a chrysalis shell 

 or a hollow cylinder of paper may be many times perforated by the 

 ovipositor, hut never will an egg be laid. The importance of tactile 

 hull in the oviposition response of flabrobrac&fi juglandU has 

 recently been shown by Hase (Die Naturwissenschaft, Jahrg. 11, 

 Heft 39, pp. 801 806, L023). Touch is probably the directing sense 

 in the oviposition behavior of Habrocytus (61). 



In a recent publication, Howard (36, p. 36 37) declares that the 

 stimulus for oviposition in certain chalcidoid parasites of gall-mak- 



