Dionysius is a Greek name from scripture; it's English/French cognate is Dennis — ten-to-one, our subject's middle name was Riester.

(When a German born in the 19th-Century vacillates between Germany and France as their birthplace, as Catharine does, it's likely they were born in Alsace-Lorraine, an ethnic German enclave in France alternately ruled by France and Germany; and Catharine does give Alsace as her mother's birthplace.)

1.  LDS.  Family Search: Internet Genealogy Service:  IGI - International Genealogical Index (online at FamilySearch.org).

Dionysius STRAUB, Christening: 10 Oct 1819 Father: Thaddaeus STRAUB; Mother: Prisca RIESTER Location: Katholisch, Felldorf, Schwarzwaldkreis, Wuerttemberg Source: LDS Film #0958273: Kirchenbuch, 1801-1968, Katholische Kirche Felldorf (OA. Horb)

"Kreis" are civil districts roughly equivalent to U.S. counties.  A translation of "Schwarz-wald-kreis" would be Black Forest District.

2a.  St. Louis, Missouri, Marriages, 1804-76 (online at Ancestry.com):

Dionisius Straub

Emeline Chapmen

6 Dec 1865

v. 12 / p. 084

2b.  LDS.  Family Search: Internet Genealogy Service:  IGI - International Genealogical Index (online at FamilySearch.org).

William STRAUB Spouse: Mary MARSH Marriage: 29 Oct 1876, Saint Louis, St Louis, Missouri Source: Marriage Records of St. Louis and St. Louis Co., 1806-1965. St. Louis (Missouri). City Recorder

Dionisious STRAUB Spouse: Nancy Ann CAGLE Marriage: 04 Jan 1881, Phelps, Missouri Source: Marriage Records, 1857-1920. Phelps County (Missouri). Recorder of Deeds

Dionisious R. STRAUB Spouse: Christina L. BURKLIN Marriage: 08 Jul 1884, Saint Louis, St Louis, Missouri Source: Marriage Records of St. Louis and St. Louis Co., 1806-1965. St. Louis (Missouri). City Recorder

William STRAUB Spouse: Emily ERMENTRAUT Marriage: 06 Sep 1885, Saint Louis, St Louis, Missouri Source: Marriage Records of St. Louis and St. Louis Co., 1806-1965. St. Louis (Missouri). City Recorder

Did Dionyius Jr. marry three times?  Or are these the marriages of a Dionysius III?

3.  1840 Census Index/Images (online at Ancestry.com):  not found (or expected) as head-of-household.  Dionysius appears to be living in his father's household in Butler Co., OH.

4.  1850 Census Every-Name-Index/Images (online at Ancestry.com; Image #205 of 334):  City of St. Louis (Ward 4), St. Louis Co., MO, Roll M432_417, p. 103A, 887/1142, enumerated 3 Sep 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):¤•

Dennis Straub	33	M		Bar Keeper	1000	Germany
Catherine	30	F				do
Demetrius	7	M				Mo
William	5	M				do
Catherine	1	F				do
Joseph	23	M		Clerk		Germany

With regard to the eldest son, it appears the enumerator was mis-hearing and/or mis-spelling, Dionysius.  One would assume Joseph STRAUB is Dennis's brother, especially as he is known to have a brother this age, but unless this Joseph managed to get unumerated twice, once here in St. Louis as a clerk and once back home in Butler Co., OH, as a cooper, these are two different Joseph's.  But if so, who is this one?

4.  1860 Census Every-Name-Index/Images (online at Ancestry.com, Image #227 of 326):  St. Louis P.O., St. Louis City (Ward 7), St. Louis Co., MO, Roll M653_653, p. 228, PN 228, 998/1638, enumerated 2 Aug 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):¤•

Dennis R. Straub	41	M		Labourer		300	Wurtemburg
Catharine   do	40	F					France
Dennis      do	17	M		Baker			Mo
Wm          do	15	M		do			do
Cate        do	11	F					do
Violet      do	9	F					do
Priska      do	7	F					do
Martha A    do	4	F					do
Francis M   do	2	M					do

Priska is a phonetic mis-spelling of the Latin name, Prisca, the pet form of which is Priscilla.

5a.  1870 Census Every-Name-Index/Images (online at Ancestry.com, Image #1107 of 7730):  Saint Louis P.O., St. Louis (Subdivision No. 14), St. Louis Co., MO, Roll M593_817, p. 550B, PN 166, 901/1336, enumerated 24 Jun 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):(¤•)

1870:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	3	4	5	6	7	9	10	11	12	19
901	1336	Straube Dennis	51	M	W	Butcher	800	Wertemburg	/	/	/
		_______ Danl	27	M	W	Policeman		Missouri	/	/	/
		_______ ???	22	F	W	Keeps H		"	/	/

Is this our subject?  If so, he and his wife have split up.  Is "Danl" our subject's son, Dionysius/Dennis?  I can't find the son anywhere else.  The young woman is indexed "Lizzie."

5b.  1870 Census Every-Name-Index/Images (online at Ancestry.com, Image #1303 of 7730):  212 North 17th Strret P.O., St. Louis (13th Subdivision), St. Louis Co., MO, Roll M593_817, p. 650A, PN 33, 197/241, enumerated 7 Jun 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):¤•

Russell Sarah	60	F	W	Nurse			Ireland
Straub Catherine	49	F	W	Keeping House		100	France
"   William	24	M	W	Ice Dealer			Missouri
"   Catherine	21	F	W	School Teacher			"
"   Viola	18	F	W	None			"
"   Priscilla	16	F	W	Dress Maker			"
"   Martha	14	F	W	"     "			"
"   Francis	12	M	W				"
"   Ida	8	F	W				"

6a.  1880 Census Every-Name-Index/Images (online at Ancestry.com, Image #39 of 44):  2024 Lucas Avenue, St. Louis (Ward 1), St. Louis Co., MO, Roll T9_720 (Book 1), p. 208C, PN 39, SD 1, ED 78, enumerated 11 Jun 1880, official enumeration date 1 Jun 1880 (extracted by Diana Gale Matthiesen):¤•

1880:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).

1

2

3

4

5

6

8

9

11

13

14

24

25

26

*

2024

220

309

Straub Catharine

W

F

60

W

Keeping house

France

France

Alsace

______ Dionisius

W

M

38

Son

W

Baker

2

Missouri

Alsace

France

______ William H

W

M

36

Son

W

Butcher

Missouri

Alsace

France

______ Martha

W

F

24

Dau

/

Milliner

Missouri

Alsace

France

______ Ida

W

F

19

Dau

/

at home

Missouri

Alsace

France

Jones Samuel

W

M

34

Boarder

/

Carpenter

Wales

Wales

Wales

*Lucas Avenue

The children's father was born in Wuerttemberg, but it appears Catharine was born in Alsace, France. They've managed to get enumerated twice, once in June (before Ida married) and again in November (after Ida married).

6b.  1880 Census Every-Name-Index/Images (online at Ancestry.com, Image #4 of 20):  2024 Lucas Avenue, City of Saint Louis, Saint Louis Co., MO, Roll T9_730, p. 206D, PN 4, SD 81, ED 194, enumerated 8 Nov 1880, official enumeration date 1 Jun 1880 (extracted by Diana Gale Matthiesen):¤-

1880:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).

1

2

3

4

5

6

8

9

10

11

13

24

25

26

*

2024

27

46

Taunehill Sam J

W

M

23

/

Clerk in P.O.

PA

Ger

Ger

_________ Ida M

W

F

19

Wife

/

Keeps house

MO

Fra

Fra

Straub Kate

W

F

61

M-in-law

/

Fra

Fra

Fra

______ Dennis

W

M

37

B-in-law

/

Baker

MO

Fra

Fra

______ William

W

M

35

B-in-law

/

Butcher

MO

Fra

Fra

Loeblein George

W

M

24

Lodger

/

Collar maker

MO

Ger

Ger

Kellerman William

W

M

27

Lodger

/

Collar maker

MO

Ger

Ger

*Lucas Avenue

They've managed to get enumerated twice, once in June (before Ida married) and again in November (after Ida married).

7.  1890 Census:  the 1890 Census Population Schedules were destroyed.

8.  1900 Census Every-Name-Index/Images (online at Ancestry.com):  not found, at least not in St. Louis.

9.  St. Louis City Death Records, 1850-1908 (online at Ancestry.com):

Name:	Dennis R Straub
Death Date:	04 Nov 1870
Address:	24th & Morgan
Volume:	4
Page:	39
County Library:	RDSL 12
Missouri Archive:	C 10370
SLGS Rolls:	311

10a.  Military Records of Individual Civil War Soldiers.  Historical Data Systems, Kingston, MA (online at Ancestry.com):

Name:	Dennis STRAUB
Side Served:	Union
State Served:	Missouri
Service Record:	Enlisted as a Corporal. Enlisted in Company C, 33rd Infantry Regiment Missouri.

10b.  Civil War Soldiers and Sailors System.  National Park Service.  (online at www.itd.nps.gov/cwss/ and at Ancestry.com):

Name:	Dennis B. STRAUB
Side:	Union
Regiment State Origin:	Missouri
Regiment Name:	33 Missouri Infantry
Regiment Name Expanded:	33rd Regiment, Missouri Infantry
Company:	C
Rank In:	Corporal
Rank In Expanded:	Corporal
Rank Out:	Private
Rank Out Expanded:	Private
Film Number:	M390 roll 47

The fact that he mustered in as a Corporal suggests he had had prior military service.

10c.  Civil War Pension Index (index and images online at Ancestry.com):

Name of Soldier	Straub, Dennis R.
Name of Dependent	Widow	Straub, Catharine
	Minor
Service	C. 33 Mo. Inf.
Date of Filing	Claim	Application No.	Certificate No.	State from which Filed
	Invalid
18?? Aug 14	Widow	476,614	399,572	Mo
	Minor

I can't read the year, but it might be 1892.  So, is this our subject or his son?  Our subject was rather old to have served, and if our subject died in 1870, why would the widow have waited so long to apply?  So did Dennis, Jr., marry again?  To a Catharine?