HOWARDULA BENIGNA 



A nemic parasite of the Cucumber-beetle, (Diabrotica) 

 CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY X 



BY N. A. COBB 



Howardula Cobb, '21. Characters of Tylenchus Bastian, 1865, but without 

 oesophageal bulb and with a non-bulbous onchium and much reflexed ovary. 

 Female finally a flaccid, cylindroid sack, without distinct alimentary canal, and 

 otherwise very much deteriorated. Amphigonic; male, free-living. Howardula 

 is probably related to Bradynema zur Strassen 1892. The latter however is 

 anonchial, and even lacks a mouth opening. 



Howardula benigna Cobb, '21. i:i (?) ^ .... (?) <98 - (?)99 - 3 5 c BB 



2.5 ,4.0'" 4.7 4.1 L9 



Anus none or vestigial; vulva sometimes terminal; uterus nearly filling the 

 body-cavity, posteriorly packed with larvae and ante- 

 riorly with segmenting eggs, near the head in the vicinity 

 of the small spermatheca narrowed and reflexed to the 

 middle of the body, whence the narrow ovary turns for- 

 ward and ends blind near the head; onchium of adult 

 obscure but the minute mouth opening still persisting. 

 Inert, viviparous, usually all of about the same stage of 

 development in any individual host-insect, each when 

 mature containing about two thousand embryos and seg- 

 menting eggs; the larvae, of two kinds, sometimes ten 

 to twenty thousand of them, proceeding from the mother 

 nemas into the body-cavity, and thence into the sexual 

 apparatus, of the host, and so becoming deposited with 

 the eggs of the latter. See Figs. 3, 6 and 7. 



2. 16. (?)24. -95. (?)97. n = 



Larval formula : 0.5- 



2. 4 X 5. 4. 2.6 



These are the measurements of the larvae as they issue 



from the vulva. Those within the mother nema and in 



the anterior part of the uterus are considerably shorter. F H g itl 



Anus none or vestigial; tail conoid, straight, broadly ture and 



rounded or subtruncate at the terminus. After deposi- 



tion along with the beetle eggs, the young nemas moult ^^J^ actual length of 



with little increase in size; after mating, the female 



drills into the body-cavity of even very young beetle larvae of both sexes, 



sometimes to the number of thirty, but more often five or six. The following 



Waverlv Press. Baltimore, Md.. June 9. 1928. Revised and continued from Nematology X, Aug. 8. 

 1921, Waverly Press. See Science, Dec. 30, 1921. 



