THE AMERICAN ENTOMOLOGIST. 



219 



NOTES ON THE USE OF THE OVIPOSITOR IN 



THE LONG-STING ICHNEUMONS OP 



THE GENUS RHYSSA. 



A beech stump, in a slightly decayed 

 condition, has furnished me the means for 

 an interesting observation. 



It was situated near the edge of a piece of 

 woods, and when first seen was covered 

 with nearly a score of Rhyssa atrata (see 

 front page of Entomologist) and lunator 

 busily engaged in their duties of boring or 

 rather drilling for the larva; of Tremex. 



As I had seen no published account of 

 their manner of operation, by which the 

 long ovipositor could be brought into posi- 

 tion, the manifestation of it was to me new 

 and quite strange. 



The ovipositor of some of these specimens 

 measured, not 3 to 4 inches as Harris has 

 stated in his work, but 5^ inches. This 

 extreme measurement came from the black 

 species or atrata. As these insects, by 

 standing on " tip-toe " and elevating their 

 abdomen to its fullest height, can clear but 

 about 2 inches space, the problem presents 

 itself as to how can the remaining 3 inches 

 of ovipositor be disposed of in order to 

 allow the drill end to enter the perforated 

 stump. 



I observed that after raising the abdomen 

 as far as possible, the drill was worked 

 forward so as to slightly bend under, giv- 

 ing the insect a purchase on same. Then 

 followed a bearing down motion on the 

 bent tube, curving the end of the abdomen 

 forward and upward, and next forcing the 

 ovipositor, near its attached end, to curve 

 also and pass up through the abdomen, and 

 above, into a cavity which there opened for 

 its reception. 



What a strange provision of nature ! 



The cavity was enclosed by a mem- 

 branous sack, capable of great distention, 

 and while the drill was being continually 

 forced up through, it curled about within 

 the sack forming one complete bend of 

 about f inch in diameter, and another 

 partial one. When fully distended, the 

 sack was very thin, quite transparent, and 

 seemingly upon the point of bursting apart. 



But the ovipositor was in this manner 

 brought to the edge of the worm-hole, was 

 slipped in, and thus made to ease away 

 upon the distended sack which by collapsing 

 forced out again the drill by its mere 

 force of contraction. The coil now soon 

 disappeared, and the insect was fully pre- 

 pared to commence operations upon the 

 hapless Tremex. 



I found one poor atrata which could not, 

 because of some defect, force the sack 

 opening to part to receive the ovipositor. 

 Her ingenuity in endeavoring to do so was 

 quite remarkable. The tube would be 

 bent under as far as possible, and then the 

 whole weight of bod}^ and power of the 

 limbs be brought into action to force the 

 opening. It proved useless ; the force used 

 usually causing the tube to slip back and 

 straighten out behind. Then she would 

 leave the locality or opening in the stump 

 that she had selected by her antennae with 

 great care, and seek a lichen or mossy spot 

 in hopes of obtaining better control of the 

 tube. Failing here also she would become 

 quite frantic in her efforts, throwing herself 

 squat down upon the tube and twisting 

 about sideways, and endeavoring by several 

 ingenious movements to accomplish her 

 purpose. Becoming at length quite ex- 

 hausted and worn out, her hold would 

 loosen and she would fall to the ground. 

 Here regaining strength she would climb 

 back but to repeat the same failure, until 

 my net enclosed her tired body, and my 

 bottle of benzine asphyxiated her forever. 



DIMORPHISM IN LOCUSTS (Acridids.) 



BY THE EDITOR. 



In our contemporary, the Canadian En- 

 tomologist, for April of the i)resent year, 

 Mr. S. H. Scudder has an interesting com- 

 munication on this subject, giving it as his 

 belief that many of the insects that liave 

 been described under the genus Pezotettix 

 are but short-winged forms of Caloptenus. 

 He says : ^' Pezotettix plagosus Scudd. and 

 Caloptemis Turnbulli Thom. are to be 

 referred to the same species ; Pezotettix 

 abditum Dodge and Caloptenus Junius Dodge 



